When Jennifer Caprio sets out to costume a show, the first thing she does is check out its music. “I listen to it on the subway or at the gym,” she told me the other day outside the Falsettos rehearsal room. “The music tells me who the characters are.” William Finn’s music told her that these characters “are extraordinary people acting in unusual circumstances.”

They are also living in the late 1970s and in the 1980s, so one of Caprio’s next steps was to examine the period. “I had a lot of fun traveling back there,” she said, “remembering things from my childhood” – in Chatham, New Jersey. “When people remember fashion, they tend to think of decades. But the 1960s lasted until around 1972, and what we think of as the ‘80s lasted from around 1984 to 1992.” She added: “It’s more accurate to think of style periods rather than decades.”

For the first act of Falsettos, which takes place in 1979, Caprio thought of “saturate earth tones” – avocado, rusty-red, aubergine, gold. “For the second act,” she said, “We’re using more spring and summer colors that fade as the story goes along.”

Caprio, who has a bachelor’s from Ithaca College and a graduate degree from Carnegie-Mellon, had to keep in mind that “all of the characters have jobs – they’re not out clubbing every night.” They also have semi-upscale taste: “They may not shop primarily at Barneys or even Saks but they also don’t shop at Sears.” Caprio said that the characters “need to be able to move in these clothes practically, as well as execute the movement required in a musical.” The characters also need to be comfortable while doing a lot of singing. Falsettos, which marks Caprio’s second collaboration with James Lapine and William Finn (the first was The 25th Annual Putnam County Spelling Bee), is essentially sung- through.

The Falsettos costumes were devised in various ways. “About one-quarter were built from scratch,” Caprio said. “And about one-quarter were copied from vintage looks.” Another quarter are actual vintage: apparently, a fair amount of clothing from the 70s and 80s is in good enough shape to withstand eight shows a week. “There was a lot of polyester back then,” Caprio said, “though not so much on the backs of these characters.” The final quarter of the costumes are rentals or were shopped from contemporary stores. All the clothing undergoes a lot of back and forth between costumer and cast. “Of all a show’s designers,” Caprio said, “the costume person is the most literally hands-on all along the process. The set designer’s work is mostly done before tech, and the lighting designer’s job largely begins then.”

Caprio informed me that, even in a period show such as Falsettos, the shoes must be new. Why? “Equity rules,” she said, referring to the union representing theatrical performers. “The shoes may look 1980s, but they aren’t FROM the 1980s.”

Next up for Caprio is an even earlier period: 1960s. She will do the costumes for Mrs. Miller Does Her Thing, a new play written and directed by Lapine, at the Signature Theatre in Arlington, Virginia, in the late winter. The play concerns the matronly Mrs. Miller, a singer who in the ‘60s had unlikely success with her off-key renditions of pop songs like “Downtown.”

I doubt Mrs. Miller will be wearing bell bottoms.

Brendan Lemon is the editor of lemonwade.com.