ANNAPOLIS, Md. — Jenna Bush looked poised as she stepped to the podium, but she couldn't quite hide the butterflies as she stood before an eager bookstore crowd Saturday to introduce her new book, "Ana's Story: A Journey of Hope."

ANNAPOLIS, Md. — Jenna Bush looked poised as she stepped to the podium, but she couldn't quite hide the butterflies as she stood before an eager bookstore crowd Saturday to introduce her new book, "Ana's Story: A Journey of Hope."

"This is my first day, so I'm a little nervous," the 25-year-old first daughter admitted.

Her face lit up, though, as soon as she started talking about the subject of her nonfiction narrative — a teenage mother with HIV whom she met during an internship with UNICEF in Latin America.

"Ana changed my life. She's only 17 years old, but she's lived the life of somebody so much older," Bush said. "Despite her hardships, Ana is so much like the teenagers here in the United States. She reminds me of myself at that age."

Bush, who embarks this weekend on a two-month national book tour, appears far different from the college student America knew during her father's early years in the White House. The young woman who was famously cited for underage drinking and once photographed sticking her tongue out is gone — replaced with an author who is passionate about her writing project.

If her work as a writer makes people realize she's more than a social butterfly, Bush, who also has worked as an elementary school teacher, is fine with that.

"The people that know me and love me, my students and colleagues, never had that perception of me," she told The Associated Press in a brief interview before her reading of "Ana's Story" at a Borders bookstore in Annapolis.

While her sister Barbara, who works at the Cooper-Hewitt National Design Museum in New York, maintains a low profile, Jenna has begun to reveal her devotion to education and helping the underprivileged. She said she never had a reason to interact with the media until she had something important to say — and now she does.

"I didn't have something that I was passionate about," she said.

Jenna Bush said the book came together quickly. She saw the potential in the teenager as soon as she saw her last fall at a community meeting for women and children living with HIV and AIDS. (Ana's name was changed to protect her privacy, and Bush does not reveal which country she lives in beyond saying it's in Central America.)

Bush began meeting with Ana several times a week, speaking with her — entirely in Spanish — about her difficult upbringing.

Ana was infected with HIV by her mother, and both of her parents died of AIDS. She was raised by relatives who beat her and molested by her grandmother's boyfriend. She ended up in a juvenile detention facility after running away from home. She became pregnant by her first boyfriend, who also was HIV-positive.

Bush was struck by Ana's positive outlook. She was vigilant about taking her medication and did not pass on the virus to her daughter, and she recently returned to school.

By the time Bush went home for the holidays last December, she had written several sample chapters and began shopping around her book proposal. She wrote most of "Ana's Story" between January and April, working with editors at HarperCollins over e-mail.

The book runs more than 300 pages, but it's written in simple language directed at teenage readers. The chapters are short, and the book includes dozens of color photographs taken by Bush's close friend, Mia Baxter, who also interned with UNICEF.

Bush said she started by writing longer, more conventional chapters, but "it just really was too much. It was too heavy, and I thought kids would find it really grueling and not at all optimistic or fun to read."

Several people in the audience said they admired the president's daughter for educating children about such difficult subject matter.

"What she's doing is a humanitarian effort that crosses political lines. It helps people to see her in a different light — different than some of the bad press she's gotten in the past," said Angela Patterson, 46, sitting next to her daughter, Lyndsay, 13. "It's hard to live your life under a microscope. She's obviously matured."