SÃO PAULO, Brazil — As a young boy in Brazil’s heartland, Carol Marra watched her parents politely correct strangers who said what a pretty daughter they had. In her teenage years, she coveted the boyfriends of her female classmates and tried out androgynous outfits, dutifully changing back into a young man’s clothes in her car before returning home.

Now a favorite among Brazil’s growing class of transgender models, Ms. Marra, 26, has become a star. She filmed two mini-series for major Brazilian television channels, is starting a lingerie line, and was the first transgender model to walk Fashion Rio — considered a top national runway event — and also the first to pose for Revista Trip, a Brazilian culture magazine that features female nudes.

Her popularity points to striking, if precarious, gains in Brazil’s popular culture for Ms. Marra and her small number of peers. In a country that publicly celebrates its mixed-race and multicultural heritage, Brazil’s cosmopolitan capitals like São Paulo and Rio de Janeiro have become places where crossing gender lines is increasingly accepted. Still, transgender models themselves say Brazil is also in many ways a deeply conservative country with strong religious forces that can create a hostile environment for its gay and transgender population.