Exhibit 99.1

ADMINISTAFF ANNOUNCES RECORD EARNINGS PER SHARE

·   Earnings per share increase 70% on 12% revenue growth

·   Operating income increases 79%

·   EBITDA increases 44% to $24 million

HOUSTON - May 1, 2008 - Administaff, Inc. (NYSE: ASF), a leading provider of human resources services for small and medium-sized businesses, today announced a 70.0% increase in diluted earnings per share to $0.51 compared to $0.30 in the first quarter of 2007. Net income increased to $13.2 million from $8.4 million in the 2007 period.

“Our record results, in the face of a slowing economy, confirm the strength and resiliency of our business model,” said Paul J. Sarvadi, Administaff chairman and chief executive officer. “Although we are experiencing slightly slower unit growth, we are meeting our profitability targets due to effective pricing and direct cost management. As these trends continue for the balance of the year, we will make the investments necessary to accelerate growth and profitability in 2009.”

Revenues for the first quarter of 2008 increased 11.8% over the 2007 period to $456.1 million, due to an 8.3% increase in the average number of worksite employees paid per month and a 3.3% increase in revenues per worksite employee per month.

Gross profit increased 27.2% over the first quarter of 2007 to $86.6 million on the growth in the average number of worksite employees paid and an increase in the average gross profit per worksite employee per month to $254 from $216 in the 2007 period. These results were at the high end of the company’s forecasted range primarily due to a higher-than-expected surplus from payroll taxes.

Operating expenses for the quarter increased 18.2% to $68.6 million, slightly below the low end of the company’s expected range, and included expected costs associated with the company’s sales expansion, middle-market and HRTools.com initiatives.

Operating income for the first quarter of 2008 increased 79.4% to $18.0 million, with an average operating income per worksite employee per month of $53 compared to $32 in the 2007 period.

EBITDA for the first quarter was $24.1 million. Cash outlays included share repurchases of $15.0 million, capital expenditures of $4.8 million and dividends of $2.9 million.

“Our solid earnings and the strength of our balance sheet have allowed us to distribute over $100 million to shareholders since January 2007 through share repurchases and dividends, which is nearly 20% of our current enterprise value,” said Douglas S. Sharp, vice-president of finance, chief financial officer and treasurer. “This not only demonstrates our commitment to maximizing shareholder return, but also our intent to take advantage of the company’s attractive valuation.”

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Administaff will be hosting a conference call today at 10 a.m. EDT to discuss these results, give guidance for the second quarter and full year 2008, and answer questions from investment analysts. To listen in, call 866-831-6224 and use passcode 25151513. The call will also be webcast at http://www.administaff.com/investor_relations. The conference call script and company guidance will be available at the same Web site later today. A replay of the conference call will be available at 888-286-8010, passcode 21908131, for two weeks after the call. The webcast will be archived for one year.

Administaff is the nation’s leading professional employer organization (PEO), serving as a full-service human resources department that provides small and medium-sized businesses with administrative relief, big-company benefits, reduced liabilities and a systematic way to improve productivity. The company operates 49 sales offices in 24 major markets. For additional information, visit Administaff’s Web site at http://www.administaff.com.

The statements contained herein that are not historical facts are forward-looking statements within the meaning of the federal securities laws (Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934). You can identify such forward-looking statements by the words “expects,” “intends,” “plans,” “projects,” “believes,” “estimates,” “likely,” “possibly,” “probably,” “goal,” “objective,” “target,” “assume,” “outlook,” “guidance,” “predicts,” “appears,” “indicator” and similar expressions. Forward-looking statements involve a number of risks and uncertainties. In the normal course of business, Administaff, Inc., in an effort to help keep our stockholders and the public informed about our operations, may from time to time issue such forward-looking statements, either orally or in writing. Generally, these statements relate to business plans or strategies, projected or anticipated benefits or other consequences of such plans or strategies, or projections involving anticipated revenues, earnings, unit growth, profit per worksite employee, pricing, operating expenses or other aspects of operating results. We base the forward-looking statements on our current expectations, estimates and projections. These statements are not guarantees of future performance and involve risks and uncertainties that we cannot predict. In addition, we have based many of these forward-looking statements on assumptions about future events that may prove to be inaccurate. Therefore, the actual results of the future events described in such forward-looking statements could differ materially from those stated in such forward-looking statements. Among the factors that could cause actual results to differ materially are: (i) changes in general economic conditions; (ii) regulatory and tax developments and possible adverse application of various federal, state and local regulations; (iii) increases in health insurance costs and workers’ compensation rates and underlying claims trends, financial solvency of workers’ compensation carriers and other insurers, state unemployment tax rates, liabilities for employee and client actions or payroll-related claims, changes in the costs of expanding into new markets, and failure to manage growth of our operations; (iv) the effectiveness of our sales and marketing efforts; (v) changes in the competitive environment in the PEO industry, including the entrance of new competitors and our ability to renew or replace client companies; and (vi) our liability for worksite employee payroll and benefits costs; and (vii) an adverse final judgment or settlement of claims against Administaff. These factors are discussed in further detail in Administaff’s filings with the U.S. Securities and Exchange Commission. Any of these factors, or a combination of such factors, could materially affect the results of our operations and whether forward-looking statements we make ultimately prove to be accurate.

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Administaff, Inc.

Summary Financial Information

(in thousands, except per share amounts and statistical data)

	March 31,			December 31,
	2008			2007
	(Unaudited)
Assets
Cash and cash equivalents	$	159,311		$	135,793
Restricted cash		34,729			35,318
Marketable securities		25,942			74,880
Accounts receivable		159,499			134,834
Prepaid expenses and other current assets		30,273			28,668
Income taxes receivable		—			3,918
Total current assets		409,754			413,411
Property and equipment, net		79,066			77,941
Deposits		70,735			63,720
Other assets		13,421			5,579
Total assets	$	572,976		$	560,651
Liabilities and Stockholders’ Equity
Accounts payable	$	4,457		$	5,236
Payroll taxes and other payroll deductions payable		111,127			113,929
Accrued worksite employee payroll expense		137,643			110,406
Accrued health insurance costs		14,126			19,297
Accrued workers’ compensation costs		36,882			37,150
Deferred income taxes		2,480			1,066
Income tax payable		888			—
Other accrued liabilities		18,218			28,518
Current portion of capital leases		640			629
Total current liabilities		326,461			316,231
Long-term capital leases		373			537
Accrued workers’ compensation costs		41,991			39,116
Deferred income taxes		6,827			6,092
Total noncurrent liabilities		49,191			45,745
Stockholders’ equity:
Common stock		309			309
Additional paid-in capital		138,780			138,640
Treasury stock, cost		(135,368	)		(123,600	)
Accumulated other comprehensive income, net of tax		14			5
Retained earnings		193,589			183,321
Total stockholders’ equity		197,324			198,675
Total liabilities and stockholders’ equity	$	572,976		$	560,651

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Administaff, Inc.

Summary Financial Information (continued)

(in thousands, except per share amounts and statistical data)

(Unaudited)

	Three months ended March 31,
	2008			2007			Change
Operating results:
Revenues (gross billings of $2.554 billion and $2.275 billion less worksite employee payroll cost of $2.098 billion and $1.867 billion, respectively)	$	456,066		$	407,758			11.8%
Direct costs:
Payroll taxes, benefits and workers’ compensation costs		369,459			339,691			8.8%
Gross profit		86,607			68,067			27.2%
Operating expenses:
Salaries, wages and payroll taxes		36,979			32,045			15.4%
Stock-based compensation		2,385			1,308			82.3%
General and administrative expenses		18,739			15,946			17.5%
Commissions		3,094			2,919			6.0%
Advertising		3,778			2,102			79.7%
Depreciation and amortization		3,646			3,720			(2.0)%
Total operating expenses		68,621			58,040			18.2%
Operating income		17,986			10,027			79.4%
Other income (expense):
Interest income		2,507			2,997			(16.3)%
Other, net		(33	)		(23	)		(43.5)%
Income before income tax expense		20,460			13,001			57.4%
Income tax expense		7,304			4,608			58.5%
Net income	$	13,156		$	8,393			56.7%
Diluted net income per share of common stock	$	0.51		$	0.30			70.0%
Diluted weighted average common shares outstanding		25,756			28,176

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Administaff, Inc.

Summary Financial Information (continued)

(in thousands, except per share amounts and statistical data)

(Unaudited)

	Three months ended March 31,
	2008		2007		Change
Statistical data:
Average number of worksite employees paid per month		113,541		104,881		8.3%
Revenues per worksite employee per month(1)	$	1,339	$	1,296		3.3%
Gross profit per worksite employee per month		254		216		17.6%
Operating expenses per worksite employee per month		201		184		9.2%
Operating income per worksite employee per month		53		32		65.6%
Net income per worksite employee per month		39		27		44.4%

⁽¹⁾ Gross billings of $7,497 and $7,229 per worksite employee per month, less payroll cost of $6,158 and $5,933 per worksite employee per month, respectively.

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Administaff, Inc.

Summary Financial Information (continued)

(in thousands, except per share amounts and statistical data)

(Unaudited)

GAAP to Non-GAAP Reconciliation Tables

	Three months ended March 31,
	2008			2007			Change
Payroll cost (GAAP)	$	2,097,588		$	1,866,759			12.4%
Less: Bonus payroll cost		(234,524	)		(235,995	)		(0.6)%
Non-bonus payroll cost	$	1,863,064		$	1,630,764			14.2%
Payroll cost per worksite employee (GAAP)	$	6,158		$	5,933			3.8%
Less: Bonus payroll cost per worksite employee		(689	)		(750	)		(8.1)%
Non-bonus payroll cost per worksite employee	$	5,469		$	5,183			5.5%

Non-bonus payroll cost represents payroll cost excluding the impact of bonus payrolls paid to the company’s worksite employees. Bonus payroll cost varies from period to period, but has no direct impact to the company’s ultimate workers’ compensation costs under the current program. As a result, Administaff management refers to non-bonus payroll cost in analyzing, reporting and forecasting the company’s workers’ compensation costs.

	Three months ended March 31,
	2008		2007		Change
Net income (GAAP)	$	13,156	$	8,393		56.7%
Interest expense		21		32		(34.4)%
Income tax expense		7,304		4,608		58.5%
Depreciation and amortization		3,646		3,720		(2.0)%
EBITDA	$	24,127	$	16,753		44.0%

EBITDA represents net income computed in accordance with generally accepted accounting principles (“GAAP”), plus interest expense, income tax expense, depreciation and amortization expense. Administaff management believes EBITDA is often a useful measure of the company’s operating performance, as it allows for additional analysis of the company’s operating results separate from the impact of taxes and capital and financing transactions on earnings.

Non-bonus payroll and EBITDA are not financial measures prepared in accordance with GAAP and may be different from similar measures used by other companies. Non-bonus payroll and EBITDA should not be considered as a substitute for, or superior to, measures of financial performance prepared in accordance with GAAP. Administaff includes non-bonus payroll and EBITDA in this press release because the company believes they are useful to investors in allowing for greater transparency related to the costs incurred under the company’s workers’ compensation program and the company’s operating performance during the periods presented. Investors are encouraged to review the reconciliation of the non-GAAP financial measures used in this press release to their most directly comparable GAAP financial measures as provided in the tables above.

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