Veggie Grill, a Santa Monica-headquartered fast-casual vegetarian restaurant chain, announced Monday it had raised $20 million in a fourth equity funding round that will be used to open new restaurants.

The company, co-founded by T.K. Pillan and Kevin Boylan, operates 16 restaurants in three states. West L.A. private equity firm Brentwood Associates, which became an investor in the last funding round in 2011, has added to its minority stake to become the largest single shareholder. Brentwood Partner Bill Barnum and Managing Director Rahul Aggarwal will join Veggie Grill’s board of directors. New and existing investors also participated, Veggie Grill said, but were not named.

Chief Executive Greg Dollarhyde said that the company is on track to double its store count within the next 18 months.

“This additional capital base will support our aggressive growth plans to meet the increasing consumer demand for delicious, vegetarian food,” Dollarhyde said in a statement.