She's bird-delicate, tiny. But there's a force about Julia Alvarez -- in her passion, urgency, outrage -- reminiscent of other diminutive writers with large things on their minds: Joan Didion, Joyce Carol Oates, Nadine Gordimer. She's been famous for 15 years, since the publication of her wildly successful novel How the Garcia Girls Lost Their Accents, but she's been working at writing for more than 35, challenging herself at every turn, daring herself to remain relevant in a profession that offers no blueprint.

She was born in New York City in 1950, during her parents' first attempt to relocate to America. They were Dominican Republicans who decided very quickly that they preferred the unforgiving dictatorship of Rafael Trujillo to a country they didn't understand. They returned to raise their children in Santo Domingo until her father became so implicated in the rebel underground that the family was forced to escape to America three months before that underground's founders, the Mirabal sisters (known as "the Butterflies"), were led to a cane field and brutally strangled. Alvarez was 10 years old. It was from the lives of the Mirabal sisters that Alvarez eventually fashioned her stirring political novel, In the Time of the Butterflies (1994). The book was a radical departure from Garcia Girls -- redefining her as a writer who wanted to do more than record immigrant experiences. She had determined to dig deeper, into the societies from which they had sprung.

Since then, she has written poetry (The Other Side/El otro lado, 1995), essays about identity (Something to Declare, 1998), a novel about a Dominican poet in exile (In the Name of Salome, 2000), and a spate of children's and young adult fiction. Every time she produces a new book, it's because she has something different to say.

Her next novel -- the one that has spurred her to weigh the relevance of the writer in the larger world -- is tentatively titled Saving the World (April, 2006), and it concerns Dr. Francisco de Balmis, a Spanish doctor who, in 1803, organized the first worldwide medical expedition to eradicate disease. Balmis set forth with the Spanish king's blessing, in a public relations mission meant to win back the colonists' hearts during a fractious, rebellious time. The object was smallpox, which had by then cut a deadly course through humanity. Balmis traveled from Spain to Colombia, Ecuador, Venezuela, Peru, Mexico, the Philippines and China, carrying the cure in the form of 22 orphan boys who harbored the vaccine in vivo. It was, after all, before the age of refrigeration. Thousands upon thousands of lives were saved.

Perhaps it's Alvarez's passion for teaching -- she's taught English at Middlebury College for many years -- that predisposes her to think history has lessons in this day of borderless scourges. "Sometimes a story just hits you upside the head," she says, "and you realize: I'm a human being in a larger world of human beings. Everything is global now." The immigrant tale is done. Over there has become over here. And nothing is alien any more.

-- Marie Arana