UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE TO

(Rule 13e-4)

Tender Offer Statement Under Section 14(d)(1) or 13(e)(1)

of the Securities Exchange Act of 1934

(Amendment No. 1)

Quest Software, Inc.

(Name of Subject Company (Issuer) and Filing Person (Offeror))

COMMON STOCK

No Par Value

(Title of Class of Securities)

74834T103

(CUSIP Number of Class of Securities)

Scott J. Davidson

Senior Vice President and Chief Financial Officer

Quest Software, Inc.

5 Polaris Way

Aliso Viejo, California 92656

(949) 754-8000

(Name, address and telephone number of person authorized to receive notices and

communications on behalf of filing person)

Copies to:

Frederick T. Muto, Esq.

Jason L. Kent, Esq.

Cooley Godward Kronish LLP

4401 Eastgate Mall

San Diego, California 92121

(858) 550-6000

CALCULATION OF FILING FEE

Transaction Valuation*	Amount of Filing Fee**
$140,012,000	$5,502.48

* Calculated solely for purposes of determining the filing fee. This amount assumes that 9,656,000 shares of common stock of Quest Software, Inc. at the maximum tender offer price of $14.50 per share will be purchased pursuant to this offer.

** The amount of the filing fee, calculated in accordance with Rule 0-11 of the Securities Exchange Act of 1934, as amended, equals $39.30 per million of the aggregate amount of transaction value.

x Check the box if any part of the fee is offset as provided by Rule 0-11(a)(2) and identify the filing with which the offsetting fee was previously paid. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

Amount Previously Paid: $5,502.48	Filing Party: Quest Software, Inc.
Form or Registration No.: Schedule TO	Date Filed: November 7, 2008

¨ Check the box if the filing relates solely to preliminary communications made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the statement relates:

¨ Third-party tender offer subject to Rule 14d-1.

x Issuer tender offer subject to Rule 13e-4.

¨ Going-private transaction subject to Rule 13e-3.

¨ Amendment to Schedule 13D under Rule 13d-2.

Check the following box if the filing is a final amendment reporting the results of the tender offer:  ¨

INTRODUCTION

This Amendment No. 1 (this “Amendment”) amends and supplements the Tender Offer Statement on Schedule TO originally filed with the Securities and Exchange Commission (the “SEC”) on November 7, 2008 (the “Schedule TO”), relating to the offer by Quest Software, Inc., a California corporation (“Quest”), to purchase up to 9,656,000 shares of its common stock, no par value per share, at a price not greater than $14.50 nor less than $12.50 per share, net to the seller in cash, less any applicable withholding taxes and without interest, upon the terms and subject to the conditions set forth in the Offer to Purchase for Cash dated November 7, 2008 (the “Offer to Purchase”), and in the related Letter of Transmittal (the “Letter of Transmittal”), which together, as each may be amended and supplemented from time to time, constitute the tender offer.

This Amendment is intended to satisfy the reporting requirements of Rule 13e-4(c)(3) of the Securities Exchange Act of 1934, as amended. The information contained in the Offer to Purchase and the related Letter of Transmittal is incorporated herein by reference in response to all of the items of this Schedule TO, except that such information is hereby amended and supplemented to the extent specifically provided herein.

Item 10(b) of the Schedule TO is hereby amended and restated as follows:

(b) Pro Forma Financial Information. The information set forth in the Offer to Purchase under Section 16, Financial Information, is incorporated herein by reference.

Items 1 through 11 of the Schedule TO, to the extent such Items incorporate by reference the information contained in the Offer to Purchase, and the Offer to Purchase, a copy of which was filed with the Schedule TO as Exhibit (a)(1)(A), are hereby amended and supplemented as follows in response to comments from the SEC and to reflect recent developments relating to Quest:

(1) The cover, Summary Term Sheet, Section 2, Background and Purpose of the Tender Offer, and Section 11, Interests of Directors and Executive Officers; Transactions and Arrangements Concerning the Shares, of the Offer to Purchase are hereby amended and supplemented as follows:

While Vincent C. Smith, our Executive Chairman of the Board, previously indicated he intended to tender 3,000,000 shares at $13.50, he subsequently informed us he now intends to tender 3,000,000 shares at $12.50.

(2) The Summary Term Sheet of the Offer to Purchase is hereby amended by inserting the following at the end thereof:

What is the accounting treatment of the tender offer?

The accounting for our purchase of shares in the tender offer will result in a reduction of our shareholders’ equity in an amount equal to the aggregate purchase price of the shares we purchase plus associated fees and expenses. The same amount will be reflected in the aggregate as reductions in cash and cash equivalents and long-term marketable securities, offset by an increase in prepaid expenses and other current assets.

(3) Section 1, Number of Shares; Proration, of the Offer to Purchase is hereby amended by adding the following sentence at the end of the fourth paragraph thereof:

If we determine that there is a reasonable likelihood that we will not be able to purchase the number of shares we intend to purchase in the tender offer in compliance with legal restrictions on our ability to complete distributions to shareholders (such as dividends and share repurchases) imposed on us as a California corporation, we may decrease the number of shares we seek, which may result in an extension of the tender offer as discussed above.

(4) Section 2, Background and Purpose of the Tender Offer, of the Offer to Purchase is hereby amended by adding the following paragraph at the bottom of page 10:

The accounting for our purchase of shares in the tender offer will result in a reduction of our shareholders’ equity in an amount equal to the aggregate purchase price of the shares we purchase plus associated fees and expenses. The same amount will be reflected in the aggregate as reductions in cash and cash equivalents and long-term marketable securities, offset by an increase in prepaid expenses and other current assets.

(5) Section 7, Certain Conditions of the Tender Offer, of the Offer to Purchase is hereby amended by adding the following sentence at the beginning of the last paragraph thereof:

The determinations referred to in paragraphs (i) and (j) above will be made by us on or about the last business day prior to the expiration date by reference to the continued listing requirements of the NASDAQ Global Select Market and applicable legal restrictions under California law, respectively, in each case as then in effect.

(6) Section 9, Source and Amount of Funds, of the Offer to Purchase is hereby amended by replacing the last sentence of the second paragraph thereof with the following:

The tender offer is not conditioned on the receipt of financing and we do not have any alternative financing plans with respect to the tender offer.

(7) Section 10, Certain Information About Us, of the Offer to Purchase is hereby amended by replacing the last bullet point of the fourth paragraph thereof with the following:

• our Current Reports on Form 8-K filed with the SEC on January 9, 2008, February 25, 2008, March 6, 2008, March 11, 2008, May 8, 2008 (excluding information therein which is deemed furnished and not filed), September 15, 2008, October 8, 2008, October 30, 2008, November 6, 2008, November 26, 2008 and December 2, 2008.

(8) Section 13, Certain U.S. Federal Income Tax Consequences, of the Offer to Purchase is hereby amended by replacing the first paragraph thereof with the following:

The following discussion is a summary of certain U.S. federal income tax consequences to our shareholders of an exchange of shares for cash pursuant to the tender offer. The discussion does not consider the effect of any alternative minimum taxes or foreign, state, local or other tax laws, or any U.S. tax considerations (e.g., estate or gift tax) other than U.S. federal income tax considerations. Further, this summary assumes that shareholders hold their shares as “capital assets” (generally, property held for investment) within the meaning of section 1221 of the Code and generally assumes that they did not receive their shares through the exercise of employee stock options or otherwise as compensation.

(8) Item 16, Financial Statements, of the Offer to Purchase is hereby amended by inserting the following at the end thereof:

Unaudited Pro Forma Consolidated Financial Information. Set forth below is condensed unaudited pro forma consolidated financial information for Quest based on historical information which has been adjusted to give effect to the transactions described below. This information should be read in conjunction with the Summary Historical Consolidated Financial Data set forth above and our audited consolidated financial statements and the related notes filed as part of our Annual Report on Form 10-K for the year ended December 31, 2007 and the unaudited condensed consolidated financial statements and the related notes filed as part of our Quarterly Report on Form 10-Q for the quarter ended September 30, 2008. This condensed unaudited pro forma consolidated financial data is not necessarily indicative of either our financial position or results of operations, which actually would have been attained, had the purchase of shares pursuant to the tender offer and the related financing been completed at the dates indicated, or, will be achieved in the future. This condensed unaudited pro forma consolidated financial data has been included herein for informational and comparative purposes only. We have included the condensed unaudited pro forma consolidated financial data solely for the purpose of providing shareholders with information that may be useful for purposes of considering and evaluating the tender offer. Our future results are subject to prevailing economic and industry specific conditions and financial, business and other known and unknown risks and uncertainties, certain of which are beyond our control. These factors include, but are not limited to, those described in this offer to purchase under “Forward-Looking Statements.”

The pro forma condensed consolidated income statements have been adjusted to give effect to the following transactions as if they had occurred at the beginning of the periods presented and the pro forma condensed consolidated balance sheet has been adjusted to give effect to the following transactions as if they had occurred at the balance sheet date:

• The purchase of common shares in the tender offer, for an aggregate purchase price of $140,012,000 at $14.50 per share or $120,700,000 at $12.50 per share;

• The sale of $42.9 million of long-term marketable securities; and

• The payment of $2.1 million in fees and expenses.

QUEST SOFTWARE, INC.

PRO FORMA CONSOLIDATED BALANCE SHEET

(In thousands)

	September 30, 2008
	Historical			Adjustments			Pro Forma at $14.50 per share			Pro Forma at $12.50 per share
ASSETS
Current assets:
Cash and cash equivalents	$	280,491		$	(99,294	)(1)	$	181,197		$	200,497
Restricted cash		2,370			—			2,370			2,370
Short-term marketable securities		686			—			686			686
Accounts receivable, net		118,207			—			118,207			118,207
Prepaid expenses and other current assets		19,764			96	(2)		19,860			19,860
Deferred income taxes		12,936			—			12,936			12,936
Total current assets		434,454			(99,198	)		335,256			354,556
Property and equipment, net		77,495			—			77,495			77,495
Long-term marketable securities		91,259			(42,907	)(3)		48,352			48,352
Intangible assets, net		115,250			—			115,250			115,250
Goodwill		669,385			—			669,385			669,385
Deferred income taxes		15,349			—			15,349			15,349
Other assets		21,187			—			21,187			21,187
Total assets	$	1,424,379		$	(142,105	)	$	1,282,274		$	1,301,574
LIABILITIES AND SHAREHOLDERS’ EQUITY
Current liabilities:
Accounts payable	$	3,768		$	—		$	3,768		$	3,768
Accrued compensation		42,577			—			42,577			42,577
Other accrued expenses		41,427			—			41,427			41,427
Current portion of deferred revenue		247,962			—			247,962			247,962
Total current liabilities		335,734			—			335,734			335,734
Long-term liabilities:
Long-term portion of deferred revenue		64,221			—			64,221			64,221
Long-term portion of income taxes payable		32,673			—			32,673			32,673
Other long-term liabilities		5,103			—			5,103			5,103
Total long-term liabilities		101,997			—			101,997			101,997
Shareholders' equity:
Common stock		885,323			(142,105	)(4)		743,218			762,518
Retained earnings		103,599			(426	)(5)		103,173			103,173
Accumulated other comprehensive loss		(2,274	)		426	(5)		(1,848	)		(1,848	)
Total shareholders' equity		986,648			(142,105	)		844,543			863,843
Total liabilities and shareholders' equity	$	1,424,379		$	(142,105	)	$	1,282,274		$	1,301,574
Book Value per Share (6)	$	9.35					$	8.81		$	9.01
Number of shares used in book value per share calculation		105,541						95,885	(7)		95,885	(8)

(1) Net adjustments to cash and cash equivalents of $99.3 million assumes the use of $140.0 million of cash for share repurchases in the tender offer plus $2.1 million in estimated fees and expenses associated with the tender offer minus $42.8 million in net proceeds from the sale of long-term marketable securities.

(2) Net adjustments to prepaid expenses and other current assets assumes the reduction of $0.1 million in accrued interest receivable from the sale of long-term marketable securities offset by an increase of $0.2 million in income taxes receivable representing the tax impact from realized losses on the sale of long-term marketable securities.

(3) Represents the amount of long-term marketable securities sold to help fund our shares repurchased.

(4) Net adjustments to common stock of $142.1 million assumes the use of $140.0 million of cash for share repurchases in the tender offer plus $2.1 million in estimated fees and expenses associated with the tender offer.

(5) Adjustments represent the recognition of realized losses from the sale of $42.9 million of our long-term marketable securities in connection with the tender offer.

(6) Book value per share is calculated by dividing the total shareholder’s equity by the common shares outstanding at September 30, 2008.

(7) Common stock outstanding was adjusted assuming that we repurchase $140.0 million in value of shares at $14.50 per share (or 9,656,000 shares) in the tender offer.

(8) Common stock outstanding was adjusted assuming that we repurchase $120.7 million in value of shares at $12.50 per share (or 9,656,000 shares) in the tender offer.

QUEST SOFTWARE, INC.

PRO FORMA CONSOLIDATED INCOME STATEMENT

(In thousands, except per share data)

	Twelve Months Ended December 31, 2007
	Historical		Adjustments			Pro Forma at $14.50 per share			Pro Forma at $12.50 per share
Revenues:
Licenses	$	308,652	$	—		$	308,652		$	308,652
Services		322,329		—			322,329			322,329
Total revenues		630,981		—			630,981			630,981
Cost of revenues:
Licenses		6,111		—			6,111			6,111
Services		55,173		—			55,173			55,173
Amortization of purchased technology		14,459		—			14,459			14,459
Total cost of revenues		75,743		—			75,743			75,743
Gross profit		555,238		—			555,238			555,238
Operating expenses:
Sales and marketing		275,037		—			275,037			275,037
Research and development		122,592		—			122,592			122,592
General and administrative		81,758		—			81,758			81,758
Amortization of other purchased intangible assets		7,345		—			7,345			7,345
In-process research and development		220		—			220			220
Total operating expenses		486,952		—			486,952			486,952
Income from operations		68,286		—			68,286			68,286
Other income, net		22,422		(2,187	)(1)		20,235			20,235
Income before income tax provision		90,708		(2,187	)		88,521			88,521
Income tax provision		27,589		(765	)(2)		26,824			26,824
Net income	$	63,119	$	(1,422	)	$	61,697		$	61,697
Net income per share:
Basic	$	0.62				$	0.67		$	0.67
Diluted	$	0.60				$	0.65		$	0.65
Weighted average shares:
Basic		101,819					92,163	(3)		92,163	(4)
Diluted		105,284					95,628	(3)		95,628	(4)

(1) Adjustment represents the reduction of $0.9 million of interest income and a realized loss of $1.3 million as a result of the use of $42.9 million of our long-term marketable securities in connection with the tender offer that yielded a return of approximately 4.3% for the twelve months ended December 31, 2007.

(2) Income tax expense reflects the tax effects of the pro forma adjustments at the U.S. federal statutory rate of 35%.

(3) Weighted average basic and diluted common shares outstanding were adjusted assuming that we repurchase $140.0 million in value of shares at $14.50 per share (or 9,656,000 shares) in the tender offer at the beginning of the period presented.

(4) Weighted average basic and diluted common shares outstanding were adjusted assuming that we repurchase $120.7 million in value of shares at $12.50 per share (or 9,656,000 shares) in the tender offer at the beginning of the period presented.

QUEST SOFTWARE, INC.

PRO FORMA CONSOLIDATED INCOME STATEMENT

(In thousands, except per share data)

	Nine Months Ended September 30, 2008
	Historical		Adjustments			Pro Forma at $14.50 per share			Pro Forma at $12.50 per share
Revenues:
Licenses	$	241,128	$	—		$	241,128		$	241,128
Services		292,650		—			292,650			292,650
Total revenues		533,778		—			533,778			533,778
Cost of revenues:
Licenses		6,110		—			6,110			6,110
Services		46,571		—			46,571			46,571
Amortization of purchased technology		14,619		—			14,619			14,619
Total cost of revenues		67,300		—			67,300			67,300
Gross profit		466,478		—			466,478			466,478
Operating expenses:
Sales and marketing		234,604		—			234,604			234,604
Research and development		114,687		—			114,687			114,687
General and administrative		66,811		—			66,811			66,811
Amortization of other purchased intangible assets		7,730		—			7,730			7,730
In-process research and development		955		—			955			955
Total operating expenses		424,787		—			424,787			424,787
Income from operations		41,691		—			41,691			41,691
Other income, net		4,385		(1,799	)(1)		2,586			2,586
Income before income tax provision		46,076		(1,799	)		44,277			44,277
Income tax provision		7,204		(630	)(2)		6,574			6,574
Net income	$	38,872	$	(1,169	)	$	37,703		$	37,703
Net income per share:
Basic	$	0.37				$	0.40		$	0.40
Diluted	$	0.36				$	0.39		$	0.39
Weighted average shares:
Basic		104,334					94,678	(3)		94,678	(4)
Diluted		106,697					97,041	(3)		97,041	(4)

(1) Adjustment represents the reduction of $1.1 million of interest income and a realized loss of $0.7 million as a result of the use of $42.9 million of our long-term marketable securities in connection with the tender offer that yielded a return of approximately 3.7% for the nine months ended September 30, 2008.

(2) Income tax expense reflects the tax effects of the pro forma adjustments at the U.S. federal statutory rate of 35%.

(3) Weighted average basic and diluted common shares outstanding were adjusted assuming that we repurchase $140.0 million in value of shares at $14.50 per share (or 9,656,000 shares) in the tender offer at the beginning of the period presented.

(4) Weighted average basic and diluted common shares outstanding were adjusted assuming that we repurchase $120.7 million in value of shares at $12.50 per share (or 9,656,000 shares) in the tender offer at the beginning of the period presented.

(10) Section 17, Miscellaneous, of the Offer to Purchase is hereby amended by adding the following as the first paragraph thereof:

On December 2, 2008, we announced the pending resolution of the previously announced investigation by the SEC into our historical employee stock option granting practices and related accounting treatment. Without admitting or denying the allegations in the SEC’s complaint, we have agreed to settle with the SEC by consenting to the entry of a judgment enjoining future violations of certain provisions of the federal securities laws. Under the terms of the settlement, which is subject to final approval by the commissioners of the SEC, we would not be charged by the SEC with fraud and would not be required to pay any monetary penalties as part of the settlement. The settlement would completely resolve the SEC investigation into our historical stock option granting practices and related accounting treatment.

Item 12 of the Schedule TO is hereby amended and supplemented by adding the following:

(a)(5)(F) Press Release issued on December 2, 2008 (Exhibit 99.1 to our Current Report on Form 8-K, filed December 2, 2008)

SIGNATURE

After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: December 2, 2008

QUEST SOFTWARE, INC.
By:	/s/    Scott J. Davidson
	Scott J. Davidson
	Senior Vice President and Chief Financial Officer

INDEX OF EXHIBITS

Exhibit Number	Description
(a)(1)(A)*	Offer to Purchase for Cash, dated November 7, 2008
(a)(1)(B)*	Letter of Transmittal (including Guidelines for Certification of Taxpayer Identification Number on Substitute Form W-9)
(a)(1)(C)*	Notice of Guaranteed Delivery
(a)(1)(D)*	Letter from Information Agent to Brokers
(a)(1)(E)*	Letter from Brokers to Clients
(a)(1)(F)*	Form of Summary Advertisement
(a)(5)(A)*	Press Release issued on October 8, 2008 (Exhibit 99.1 to our Current Report on Form 8-K, filed October 8, 2008)
(a)(5)(B)*	Transcript of October 8, 2008 Conference Call (Exhibit 99.1 to our Schedule TO-C, filed October 10, 2008)
(a)(5)(C)*	Press Release issued on October 30, 2008 (Exhibit 99.1 to our Current Report on Form 8-K, filed October 30, 2008)
(a)(5)(D)*	Transcript of October 30, 2008 Conference Call (Exhibit 99.1 to our Schedule TO-C, filed November 3, 2008)
(a)(5)(E)*	Press Release issued on November 6, 2008 (Exhibit 99.1 to our Current Report on Form 8-K, filed November 6, 2008)
(a)(5)(F)	Press Release issued on December 2, 2008 (Exhibit 99.1 to our Current Report on Form 8-K, filed December 2, 2008)
(b)	Not applicable
(d)(1)*	Quest Software, Inc. 1999 Stock Incentive Plan, as amended (Exhibit 10.1 to our Quarterly Report on Form 10-Q for the period ended March 31, 2008, filed May 12, 2008)
(d)(2)*	Quest Software, Inc. 2001 Stock Incentive Plan, as amended (Exhibit 10.3 to our Quarterly Report on Form 10-Q for the period ended March 31, 2008, filed May 12, 2008)
(d)(3)*	Quest Software, Inc. 2008 Stock Incentive Plan (Exhibit 10.4 to our Quarterly Report on Form 10-Q for the period ended March 31, 2008, filed May 12, 2008)
(d)(4)*	Quest Software, Inc. Executive Incentive Plan (Exhibit 10.11 to our Annual Report on Form 10-K for the period ended December 31, 2007, filed February 25, 2008)
(g)	Not applicable
(h)	Not applicable

* Previously filed.