Exhibit 3.91

BY-LAWS OF
NORMAL LIFE OF LAFAYETTE, INC.

ARTICLE 1

Section 1. Annual Meeting of Shareholders

The annual meeting of the shareholders shall be held at such time, place and on such date as the Board of Directors shall designate and as stated in the notice of the meeting, said date to be no later than six months following the end of the Corporation’s fiscal year. The purpose of such meeting shall be the election of directors and the transaction of such other business as may properly come before it. If the election of directors shall not be held on the day designated for an annual meeting, or at any adjournment thereof, the Board of Directors shall cause the election to be held at a special meeting of the shareholders to be held as soon thereafter as may be practicable. Failure to hold the annual meeting at or within the designated time, or to elect directors at or within such time, shall not work forfeiture or a dissolution of the Corporation and shall not otherwise affect valid corporate acts.

Section 2. Special Meeting of Shareholders

Special meetings of the shareholders may be held whenever called in writing by vote of a majority of the Board of Directors or by the President. Notice_ of all special shareholders’ meeting, other than adjourned meetings, shall be given in the-manner prescribed for the annual

shareholders’ meeting, except the notice must be given at least two days prior to the date of the meeting. Any shareholder may waive notice of the meeting.

Section 3. Quorum

At any shareholders’ meeting, 51% of all of the shares of the company present in person or represented by proxy shall constitute a quorum for all purposes, unless by law a larger representation is required, and in that case, the percentage so prescribed by law. If the holders of stock necessary to constitute a quorum shall fail to attend in person or by proxy at an annual or special meeting, a majority of the shareholders present in person or by proxy may adjourn the meeting from time to time, without notice, other than by announcement at the meeting, until holders of stock sufficient to constitute a quorum, shall attend. At any such adjourned meeting, at which a quorum shall be present, any business may be transacted which might have been transacted at the meeting as originally called.

Section 4. Voting

At each meeting of shareholders, each shareholder shall be entitled to vote in person or by proxy, appointed by

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instrument in writing, signed by the shareholder or his authorized attorney and delivered to the Secretary of the meeting, and he shall have one vote for each share of stock standing registered in his name at the time of the closing of the transfer books for said meeting.

ARTICLE II

Section 1. Board of Directors

The Board of Directors shall consist of no less than two, nor more than seven, persons, and shall be elected by the shareholders at the annual meeting and shall hold office for one year and until their successors are elected and qualified.

Section 2. Place of Meetings

The meetings of the Board of Directors may be held at such place, whether in this state or elsewhere, as a majority of the directors may from time to time appoint.

Section 3. Regular Meetings of the Board of Directors

Regular meetings of the Board shall be held on the first day of each month if not a legal holiday, and if a legal holiday, then on the next succeeding day not a legal holiday. No notice shall be required for any regular Board meeting.

Section 4. Special Meetings of the Board of Directors

Special meetings of the Board of Directors shall be held whenever called by direction or by a majority in

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number of the directors or by the President. The Secretary shall give notice of such special meeting by mailing same at least two (2) days before the meeting, addressed to the last known address of each director, or by telephoning, telegraphing, or giving personal notice at least one (1) day before the meeting. Any director may waive notice of a special meeting. Unless otherwise indicated in the notice, any and all business may be transacted at a special meeting.

Section 5. Quorum for Meeting of Board of Directors

A majority of the Board of Directors shall constitute a quorum, and the acts of a majority at a meeting having a quorum shall constitute the acts of the Board. A majority of those present may adjourn the meeting from time to time.

Section 6. Proxy

Any director absent from a regular or special meeting may be represented by any other director or shareholder who may cast the vote of the absent director according to the written instructions, general or special, of said absent director.

Section 7. Election of Officers

At the first regular or special meeting of the new Board of Directors in each year, at which a quorum shall be present, held next after the annual meeting of the shareholders, the Board of Directors shall elect the officers of the company.

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ARTICLE III

Section 1. Officers

The officers shall be President, Secretary, and Treasurer, and such other officers as may be provided by the Board. Any two of the above named officers may be combined in one person. The officers shall hold office for one year and until their respective successors have been duly elected and qualified. However, any officer may be removed at any time by the affirmative vote of a majority of the Board of Directors.

Section 2. Powers and Duties of the President

The President shall be the chief executive officer of the company. He shall preside at all shareholders’ and directors’ meetings. He shall have supervision of the business of the company. He may sign and execute all contracts, bonds, and obligations of the company. He, along with any other officer of the company, shall sign the certificates of the shares of the capital stock of the company. He shall do and perform such other acts as may be from time to time assigned to him by the Board.

Section 3. Powers and. Duties of Vice President

Any Vice President, who is a director, shall possess the powers and perform the duties of the President in his absence or disability. In the absence of the President, he may sign and execute all bonds, contracts, and obligations in the name of the company,

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and along with any other officer he may sign all certificates of shares of the capital stock of the company. He shall do and perform such other duties as may be from time to time assigned to him by the Board. A Vice President who is not a director shall not possess the power nor perform the duties of the President in his absence or disability.

Section 4. Powers and Duties of the Secretary

The Secretary shall keep the minutes of the meetings of the shareholders and the directors, and give notices of such meetings. He shall perform in general the duties incident to the Office of Secretary, subject to the control of the Board, and shall perform such other duties as the Board may assign to him from time to time. He may sign certificates of stock of the corporation along with the President.

Section 5. Powers and Duties of the Treasurer

The Treasurer shall perform, in general, the duties incident to the office of Treasurer subject to the control of the Board, and shall perform such other duties as the Board may assign him from time to time. He may, along with the President, sign certificates of stock of the corporation.

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ARTICLE IV

Stock in Other Corporations

Unless otherwise ordered by the Board, the President, or a proxy appointed by the President, shall have full power in behalf of the company to vote at any meeting of stockholders of any corporation in which this company may hold stock, and exercise all rights and powers of such stock which the company might have exercised if present. The Board may confer like powers upon any other person or persons.

ARTICLE V

Section 1. Certificate of Shares

Each stockholder shall be entitled to a certificate signed by the President, along with any other officer. The form of certificate shall be adopted by the Board.

Section 2. Transfer of Shares

Shares shall be transferred only on the books of the company upon surrender and cancellation of certificates for a like number of shares.

Section 3. Closing of Transfer Books

The stock transfer books may be closed for a shareholders’ meeting, and for the payment of dividends during such periods as the Board may fix from time to time, and during such periods, no stock shall be transferred.

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ARTICLE VI

Signing of Checks, etc.

Checks or notes of this corporation shall be signed by such officers or persons as the Board may from time to time designate.

ARTICLE VII

Dividends on Stock

Dividends on stock of this corporation shall be payable as the Board of Directors may from time to time designate.

ARTICLE VIII

Corporate Seal

A seal with the words, NORMAL LIFE OF LAFAYETTE, INC., shall be the corporate seal of this company.

ARTICLE IX

Amendments to By-Laws

The Board of Directors shall have power to make, amend, and repeal the By-laws of the company by vote of a majority of all of the directors at any regular or special meeting, without any prior notice of intention to make, amend, or repeal the By-laws.

ARTICLE X

Indemnity

The corporation shall indemnify and hold harmless each director and officer now or hereafter serving the corporation from and against any and all claims and liabilities to which he may be or become

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subject by reason of his now or hereafter being or having heretofore been a director or officer of the corporation and/or by reason of his alleged acts or omissions as such director or officer, whether or not he continues to be such officer or director at the time when any such claim or liability is asserted, and shall reimburse each such director and officer for all legal and other expenses reasonably incurred by him in connection with defending any or all such claims or liabilities, including amounts paid or agreed to be paid in connection with reasonable settlements made before final adjudication with the approval of the Board of Directors, whether or not he continues to be such director or officer at the time such expenses are incurred; provided, however, that no director or officer shall be indemnified against any claim or liability arising out of his own negligence or willful misconduct or shall be indemnified against or reimbursed for any expenses incurred in defending any or all such claims or liability or in settling the same unless in the judgment of the directors of the corporation the director or officer against whom such claim or liability is asserted has not been guilty of negligence or willful misconduct. The foregoing right of indemnification shall not be exclusive of other rights to which any director or officer may be entitled as a matter of law.

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