Communications agency 451 Marketing has expanded its Boston headquarters.

The company now occupies a new 10,000-square-foot space on the fourth floor at 100 North Washington St. The new space is more than double the size of 451 Marketing’s previous office on the first floor of the building.

"This move was both an exciting opportunity and a necessity for 451," AJ Gerritson, 451 Marketing founding partner, said in a statement. "We’ve added more than twelve people to the Boston office in the past three months and needed room to accommodate our extraordinary growth."