It's a sign of the times that they're lining up at the Broad Street Ministry — a queue not of the homeless and others in need. Rather, it's arts groups asking to get in, eager to work with an audience with whom, a decade or so ago, they had little to do.

"Lining up, probably, is an exaggeration," says Mike Dahl, executive director of Broad Street Ministry, which is part church and part social service agency for those in the throes of poverty, addiction, homelessness, and mental illness.

But Dahl does say that he has more offers from arts groups to perform for and collaborate with his guests than can be accommodated by the ministry, which happens to be across the street from the Kimmel Center. Poets, singers, dancers, and instrumentalists want to share their art with these long-neglected audiences.

Artists have traditionally done good work with underserved audiences, but the scale of activity has grown enormously. Many arts groups have moved these kinds of programs from the periphery to their core mission. How arts groups define audience has changed, and for the better.

There's a dull phrase for the concept: audience engagement. But there's nothing dull about what hinges on the proliferation and success of the trend. For arts groups struggling for relevance, it may mean survival.

From the audience side, it gets right to the question of what it means to experience art and who gets access to it. There is probably no more critical question at a time when some forces are working to divide America into two discrete societies of haves and have-nots.

Which arts groups are looking to replace the traditional one-night stand for a deeper relationship? It might be easier to list who is not. Last season, Network for New Music developed new pieces with community poets in Germantown. Dancers from Pennsylvania Ballet II set a new work on a corps of young autistic dancers through Art-Reach, which connects the arts to low-income and disabled people. Philadelphia Orchestra composer-in-residence Hannibal Lokumbe brought his exuberant music-with-a-conscience message to prisons, schools, and churches. Curtis Institute of Music composer Emily Cooley is helping inmates at Graterford Prison to write music.

Where concerts used to be a one-way street — in which musicians played, audiences listened, and then everyone went home — many performances today are just one stop on a journey. Increasingly, audiences are a source of inspiration to artists, who mine for material in the community, sometimes performing the resulting work center stage. After Lokumbe spoke his gospel of forgiveness to area schools, some students felt invested enough to show up for concerts and other events a few days later in Center City. He will no doubt have gathered up a fan club by the time he debuts the oratorio he is composing during his residency, Healing Tones, in 2019.

Why this trend, and why now?

It's easy to question sincerity. There is philanthropic support for these kinds of activities today. Moreover, you can't help but wonder whether all this altruism would be in bloom were arts groups not struggling to keep their concert halls full. But good deeds in this world are often buoyed by a series of complex, aligned motives. Take, for instance, the argument that we should support the arts because it's good economic stimulus. It was never the best argument since it failed to convey what was most important about the arts: feeding the soul, not lining the pockets of developers.

It's still true that the real value of the arts does not show up easily in metrics. No one can say that a performance of a Schubert symphony is more meaningful to a musicologist than to a 9-year-old autistic girl or a lifer at Graterford. Theses things inevitably are personal.

And don't fall for the argument that only some people deserve to have art or beauty in their lives. It's stupendously flawed logic to believe that prisoners, because they have committed a crime — even assuming that they all have — should be deprived of art. Talking to the graduating class at Curtis in May, Los Angeles Philharmonic CEO Deborah Borda cited conductor Gustavo Dudamel, who calls music "a fundamental human right," like clean water, air, and education.

It's heartening to see so many arts groups putting that idea into action.

Philadelphia was a pioneer in the concept of arts as social fabric. Philadelphia visual artist Lily Yeh has been healing broken communities from Rwanda to North Philadelphia for decades. Soon, superstar violinist Midori promises to boost the profile of audience engagement by bringing her admirable work to Curtis.

She will find an audience of artists receptive in a way they would not have been a decade ago.

"When people come in," Dahl says of artists who visit Broad Street Ministry, "they get more than they give."