EXHIBIT 4.2

THIRD AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT

THIS AMENDMENT TO CREDIT AGREEMENT (this “Amendment”) is entered into as of July 1, 2018, by and between BARRETT BUSINESS SERVICES, INC., a Maryland corporation (“Borrower”), and WELLS FARGO BANK, NATIONAL ASSOCIATION (“Bank”).

RECITALS

WHEREAS, Borrower is currently indebted to Bank pursuant to the terms and conditions of that certain Amended and Restated Credit Agreement between Borrower and Bank dated as of June 30, 2017, as amended from time to time (the “Credit Agreement”).

WHEREAS, Bank and Borrower have agreed to certain changes in the terms and conditions set forth in the Credit Agreement and have agreed to amend the Credit Agreement to reflect said changes.

NOW, THEREFORE, for valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree that the Credit Agreement shall be amended as follows:

1.Section 1.1(a) is hereby amended and restated in its entirety to read as follows:

“(a)Line of Credit.  Subject to the terms and conditions of this Agreement, Bank hereby agrees to make advances to Borrower from time to time up to and including July 1, 2020 (the “Line of Credit”), not to exceed at any time the aggregate principal amount of Twenty Eight Million Dollars ($28,000,000), the proceeds of which shall be used to finance working capital for Borrower.  Borrower’s obligation to repay advances under the Line of Credit shall be evidenced by a promissory note dated as of

July 1, 2018, as modified from time to time (the “Line of Credit Note”), all terms of which are incorporated herein by this reference.”

2.Section 1.1(b) is hereby is hereby amended by deleting “Six Million and 00/100 Dollars ($6,000,000.00)” as the maximum aggregate undrawn amount of all outstanding Line of Credit Letters of Credit, and by substituting for said amount “Seven Million Five Hundred Thousand Dollars ($7,500,000)”.

3.The obligation of Bank to amend the terms and conditions of the Credit Agreement as provided herein, is subject to the fulfillment to Bank’s satisfaction or waiver of all of the following conditions by no later than June 29, 2018:

(a)Documentation.  Bank shall have received, in form and substance satisfactory to Bank, each of the following, duly executed:

(b)Other Fees and Costs.  In addition to Borrower’s obligations under the Credit Agreement and the other Loan Documents, Borrower shall have paid to Bank the full amount of all costs and expenses, including reasonable attorneys’ fees (including without limitation the allocated costs of Bank’s in-house counsel) expended or incurred by Bank in connection with the negotiation and preparation of this Amendment, for which Bank has made demand.

1

(c)Interest and Principal.  Interest and principal under the notes contemplated in the Credit Agreement have been paid current.

4.Except as specifically provided herein, all terms and conditions of the Credit Agreement remain in full force and effect, without waiver or modification.  All terms defined in the Credit Agreement shall have the same meaning when used in this Amendment.  This Amendment and the Credit Agreement shall be read together, as one document.

5.Borrower hereby remakes all representations and warranties contained in the Credit Agreement and reaffirms all covenants set forth therein.  Borrower further certifies that as of the date of this Amendment there exists no Event of Default as defined in the Credit Agreement, nor any condition, act or event which with the giving of notice or the passage of time or both would constitute any such Event of Default.

[REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

2

UNDER OREGON LAW, MOST AGREEMENTS, PROMISES AND COMMITMENTS MADE BY BANK CONCERNING LOANS AND OTHER CREDIT EXTENSIONS WHICH ARE NOT FOR PERSONAL, FAMILY OR HOUSEHOLD PURPOSES OR SECURED SOLELY BY THE BORROWER’S RESIDENCE MUST BE IN WRITING, EXPRESS CONSIDERATION AND BE SIGNED BY BANK TO BE ENFORCEABLE.

IN WITNESS WHEREOF, the parties hereto, intending to be legally bound hereby, have caused this Agreement to be executed as of the day and year first written above.

3