The Ha-Has comedy group was created by accident in 2003 when Pam Victor, then an improv newbie, offered to do a show at her local library—and then had to form a group to perform it. The group’s original name, The Ha-Ha Sisterhood, was also library-inspired, a play on the then-bestselling novel Divine Secrets of the Ya-Ya Sisterhood. In 10 years, the troupe, comprising Victor, Maureen McElligott, Laura Patrick and Christine Stevens, has blossomed into the Valley’s foremost purveyor of “making up funny on the spot,” as Victor terms it. Building on the improv staple of short-form sketches triggered by audience suggestions, the Ha-Has have recently branched into long-form mini-theater, like the form they call “Shrink: Where Freud Meets Funny,” imagining a week’s worth of therapy sessions, as well as seat-of-the-pants narratives built around book clubs and interviews. This weekend the group celebrates its 10-year anniversary with a show and party at their monthly gig, The Happier Valley Comedy Show.

July 13, 8 pm, Arts Block Café, 289 Main St., Greenfield, $10 at the door or $7 at theartsblock.com.