Not long ago, up-and-coming musicians who happened to be gay were faced with a difficult decision: be open about their orientation - and risk alienating mainstream audiences - or hide their private lives from fans.

Not long ago, up-and-coming musicians who happened to be gay were faced with a difficult decision: be open about their orientation — and risk alienating mainstream audiences — or hide their private lives from fans.

For singer-songwriter Mary Lambert, 25, being out from the get-go was more of a calling than a choice.

“For me, an activist role, or [standing up for] civil rights…or whatever political stance I am taking, it’s never really intentional,” she said recently from New York. “It’s just naturally who I am — someone who wants to talk about these things.”

And people want to listen. With the release of her aptly titled debut album, Heart On My Sleeve, Lambert’s audience is growing rapidly. Her U.S. tour will stop at Columbus’ A&R Music Bar on Wednesday, Oct. 29.

We spoke the day of the album’s release, Oct. 14, after her early appearance on “Good Morning America” and just before a Google Hangout session with her fans. “Everybody has been so kind and so supportive,” she said, “and I am so excited to go to sleep — it’s been a long 24 hours!”

It’s also been a whirlwind year for Lambert. In 2012, she was working as a waitress, bartender and spoken-word poet in Seattle when a friend connected her with up-and-coming hip-hop duo Macklemore & Ryan Lewis. They asked Lambert, who identifies as a lesbian, to write a musical hook for a song about gay marriage.

The song, “Same Love,” was nominated for two 2014 Grammy Awards and reached No. 11 on the Billboard Hot 100 charts in 2013. And Lambert’s simple, soulful chorus (“I can't change, even if I tried, even if I wanted to/ My love … she keeps me warm") has helped give voice to the marriage equality movement.

“When ‘Same Love’ sort of fell into my lap, I was like, this is an invitation to get into celebrity culture and hopefully shift the paradigm and be a part of a beautiful social movement,” she said. “I didn’t think that I could actually change the world through music or make a big impact, and ‘Same Love’ really showed me that I could.”

Capitol Records signed Lambert last year and connected her with co-producers who have worked with everyone from Tori Amos to Kanye West to Miley Cyrus to co-write and produce Heart On My Sleeve. The record aims for universal pop appeal with its feel-good but deeply personal songs about love, mental illness, surviving abuse and trauma, weight and body image, and coming to terms with one’s sexuality.

On “Secrets,” the current single from Heart On My Sleeve, she boldly declares, “I don’t care if the world knows what my secrets are.” Other album standouts are “Chasing the Moon,” which Lambert said she wrote about the summer before her senior year of high school, when she fell in love with her first girlfriend, and “Monochromatic,” which was inspired by feeling out of place in Los Angeles.

“I have a really hard time in L.A. because I feel like I’m walking through a room and everyone’s looking at me like I shouldn’t be wearing a crop top. And I’m like, ‘Fuck you, I should definitely be wearing a crop top!’” she said with a laugh.

As Lambert’s star has risen and her love life has prospered (she’s dating fellow singer-songwriter Michelle Chamuel), she was faced with an unexpected new challenge — writing from a place of stability.

“Songwriting for me is a form of catharsis, and it’s something that I do when I need to process something,” Lambert said. “It used to be like I needed to be drunk or crying, or I needed to be going through something deeply, severely painful to write — and sort of create chaos.”

Working on Heart On My Sleeve, she said, taught her “you don’t have to be a complete disaster to write beautiful or even sad music.”

She added, “I’m really just being myself and I want to be a part of the solution. I want to be a part of people’s healing.”