Lupoli Cos. has acquired a controlling interest in the Monarch Lofts, a 203-unit apartment complex located within the Riverwalk redevelopment in Lawrence.

The transaction, which includes the purchase of historic tax credits from previous owner and developer Robert Ansin, totals $38 million, CEO Sal Lupoli said.

The property contains unfinished former mill space that gives Lupoli the ability to add up to another 250 apartments, he said. The strategy is to expand the residential portion of the 3.6-million-square-foot mixed-use complex on the Merrimack River.

“It gives us the synergy now to market the live, work and play model,” said Lupoli, founder of the Sal’s Pizza and Salvatore’s restaurant chains.

The transaction gives Lupoli control of the entire former mill complex stretching from Interstate 495 to Union Street. The apartments are located in the former Wood Mill building across from the McGovern Transportation Center and MBTA commuter rail Lawrence station.

Lupoli has begun the permitting process with the city of Lawrence for the next residential phase, which would include 200 to 250 additional units.

Meetings with existing tenants to discuss the change of ownership and future plans will begin this month, Lupoli said.