WASHINGTON — Sister Rachel Terry has a confession to make.

“I really, really like ’90s pop music,” says the 35-year-old nun, who teaches music at Little Flower Parish elementary school in Bethesda. “I like to sing it loud in the car. I like to dance to it. TLC and Destiny’s Child? That’s my favorite music as a musician and a church member.”

Sister Rachel’s housemates appreciate her taste in pop music. They just don’t share it. Sister Ritamary, Sister Madonna Marie, Sister Saint Henry and Sister Rosemaron – the four nuns who live with Sister Rachel in the convent next to the elementary school where they work in this wealthy Washington suburb – are all four decades her senior. They’re a generation (or three) removed from such hits as “Say My Name” and “Baby-Baby-Baby.”

But if they don’t boast the same knowledge of ’90s hits, the five sisters – all members of the Immaculate Heart of Mary order – believe that what they do have in common is timeless: a desire to devote their lives to service, sacrifice, teaching and prayer, and to be a reflection, they hope, of the life of Jesus. It is a lifestyle that gives them spiritual sustenance and a guiding purpose. But finding others to share that journey is proving ever more difficult.

Fifty years ago, deciding to become a nun was not at all uncommon. The U.S. population was 195 million in 1965, and there were about 181,000 nuns, the peak number for religious sisters in the country, according to a 2009 study by the Center for Applied Research in the Apostolate at Georgetown University.

FUTURE IN DOUBT

Today there are 321 million Americans and approximately 48,000 nuns. And the vast majority of them are retired. Sixty-nine percent of all nuns are 70 or older. Just 3 percent of nuns in the United States are under age 49.

Nuns across the country are grappling with this dropoff and what it means for their futures. Though part of the Catholic Church, their orders are mostly financially independent. Now they worry about how they will pay for increasing health-care and insurance costs in their rapidly aging ranks, with many nuns no longer able to work and earn an income. They worry about whether they can even continue to exist, a concern that is all the more remarkable given what a significant role nuns played in the 20th-century American church.

The caricature of the nun is one with a rosary in one hand and a knuckle-rapping ruler in the other. But, in fact, American nuns were both leaders and foot soldiers in education, hospitals, orphanages, old-age homes and a wide range of social services. They also took lead roles in the civil rights movement and on social justice issues. For many American Catholics, their most frequent and sustained interactions with religious figures were with nuns, not priests.

As a young woman who chose to become a nun in the United States in the 21st century, Sister Rachel knows that she is a rarity. The numbers in her order reflect the national trends. There are close to 400 sisters, but only three are in their 30s. There are none in their 20s. And yet she seems thoroughly unvexed by the predicament of American nuns.

“I didn’t look at our sisters and say, ‘This is a group of dying women.’ I don’t think anyone would enter a congregation like that,” she says. “Our order is very full of life. It’s a vibrant group of women.”

When Pope Francis visits the United States next week, nuns here will be paying close attention to his words to see whether he will acknowledge their contributions and suggest what might be done to ensure their continued and vital presence. And when he celebrates Mass at Catholic University on Wednesday, Sister Rachel will be a member of the Archdiocesan Papal Mass Choir that greets him. She will not be singing “Baby-Baby-Baby.” She’ll be singing Latin chants, Aaron Copland compositions and traditional hymns in Spanish and English. And her sisters from the convent at Little Flower will be in the audience, rooting her on.

THE DECISION

“Why?”

That’s the question that Sister Rachel says she heard most about deciding to become a nun. It wasn’t asked with disapproval, but with real curiosity. Some wanted to know whether she had a Eureka moment or whether she knew all along. In Rachel’s case, the answer is neither.

As a teenager growing up in a middle-class family in Millville, N.J., in the mid-1990s, Rachel Terry wasn’t thinking about eventually living in a convent. She went to a public high school. She was a member of the band and performed in musicals and plays. She went on dates and went to prom.

“I wasn’t strongly focused on the church or religion,” she says. “It was definitely a part of my life, but it wasn’t the main thrust of my high school experience.”

That began to change when she began her freshman year at Marywood University, a small Catholic college in Scranton, Pa. Many of her teachers were nuns. They were an intrinsic part of university life, in class and outside of it.

“The spirit of the sisters was very present,” she says. “I felt this really intense connection to that spirit. And I really enjoyed the sisters because they were all the things I thought I could be: very competent, professional, happy. They loved life.”

She felt called and yet at the same time she was skeptical of that calling.

“It felt like a mind game that I was playing with myself,” she says. “So I would consistently ask for clarity, which … is not God’s major forte.

“I would do really juvenile things. Like I’d be in the practice room and say, ‘Okay, God, if I get through this whole Chopin nocturne without making one single mistake, then I’ll know that you want me to be a nun.’ And then I’d mess up all over the place. Or if I got to the end without messing up I’d say, ‘Well, that was a fluke, let me try it again.’ ”

Eventually she became more comfortable with the decision. She talked about it with her close friends. Telling her family was next.

It was the summer of 2001 when she broke the news to her parents and three siblings at the kitchen table. Her mother dropped the laundry basket she was carrying. Everyone looked stunned.

“Like anything else that a teenager does, you wonder: How long is this going to last,” says Kathleen Terry, Sister Rachel’s mother. “At first, I was confounded. But as time went by and we realized she was very serious about this, we just accepted it the way you accept whatever your children do.”

Kathleen and her husband, David, were both involved in the church and choir and music ministry. Faith was a key element of their family. It wasn’t that their daughter’s decision went against their wishes, it’s just that they knew it was a radical choice for a young woman at the time.

‘A GUTSY MOVE’

“Of course, I’m thinking, selfishly, I want grandchildren,” says Kathleen, with a laugh. She says her friends tried to get her to change her daughter’s mind and notes that at the time the church was especially unpopular because of the emerging sexual abuse scandal that was rocking the priesthood.

“We were grateful she had that strength in her, because, whoo, that was a gutsy move,” says Kathleen. “Now I think it’s the best decision she could have ever made.”

Sister Rachel knows that her decision has ruled out other possibilities. “No matter what path you choose, you’re saying yes to something and no to something else,” she says. “I’m not grieving for those things I didn’t choose.”

After Pope Francis returns to the Vatican, the fundamental issues facing American nuns will remain unchanged. The numbers will continue to decline rapidly. The financial crunch will worsen. There is no magic potion to fix that math.

What there is is what nuns have relied on for centuries: faith. For Sister Rachel, whose journey in religious life is still relatively young, faith is more than enough.

“We are not in a state of fear,” she says. “We’re in a state of, okay, how are we going to do this together? We live in a really graced state of hope. And not just optimism, but real hope that if it is to be, it will be.”