UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D. C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15 (d)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of Earliest Event Reported): June 30, 2013

FIRST FINANCIAL BANKSHARES, INC.

(Exact Name of Registrant as Specified in its Charter)

400 Pine Street, Abilene, Texas 79601

(Address of Principal Executive Offices and Zip Code)

Registrant’s Telephone Number (325) 627-7155

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

On June 30, 2013, the Company renewed its loan agreement with Frost Bank. Under the loan agreement, the Company is permitted to draw up to $25.0 million on a revolving line of credit. Prior to June 30, 2015, interest is paid quarterly at Wall Street Journal Prime and the line of credit matures June 30, 2015. If a balance exists at June 30, 2015, the principal balance coverts to a term facility payable quarterly over five years and interest is paid quarterly at the election of the Registrant at Wall Street Journal Prime plus 50 basis points or LIBOR plus 250 basis points. The line of credit is unsecured. Among other provisions in the credit agreement, the Company must satisfy certain financial covenants during the term of the loan agreement, including without limitation, covenants that require the company to maintain certain capital, tangible net worth, loan loss reserve, non-performing asset and cash flow coverage ratios. In addition, the credit agreement contains certain operational covenants, that among others, restricts the payment of dividends above 55% of consolidated net income, limits the incurrence of debt (excluding any amounts acquired in an acquisition) and prohibits the disposal of assets except in the ordinary course of business. Since 1995, the Company has declared dividends as a percentage of its consolidated net income in a range of 37% (low) in 1995 to 53% (high) in 2003 and 2006. Through the three months ended March 31, 2013, the Company has declared dividends equal to 42.4% of its consolidated net income. There have been no borrowings under the loan agreement during 2013 or 2012.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this Report to be signed on its behalf by the undersigned hereunto duly authorized.