Tennessee-based AAC Holdings Inc. has acquired Lafayette-based Townsend and its six outpatient substance abuse treatment centers in a cash and stock deal valued at $21.25 million.

The deal includes Townsend’s outpatient treatment centers in Baton Rouge, New Orleans, Covington, Metairie, Lafayette and Lake Charles; a 20-bed detox facility in Scott; and a lab. Townsend’s Houma outpatient treatment center, a separately managed joint venture between Townsend and other partners, was not part of the acquisition.

Townsend was included in Inc. magazine’s 2015 list of the 5,000 fastest-growing companies. Over the three years ending in 2014, Townsend’s revenue jumped 126 percent to $11 million. Although Inc. lists Townsend as a New Orleans firm, Townsend’s website says its corporate headquarters are in Lafayette.

The company generated around $10.9 million in revenue for the first nine months of 2015.

Under the deal, AAC subsidiary American Addiction Centers Inc. will pay $12.75 million in cash and $8.5 million in stock for Townsend.

Townsend was founded in 2009 by Dr. Howard Wetsman and Chief Executive Officer Michael Handley. They and the Townsend staff will be retained by AAC.