ORLANDO, Fla. — Two decades ago, Harris Rosen, who grew up poor on the Lower East Side of Manhattan and became wealthy in the Florida hotel business, decided to shepherd part of his fortune into a troubled community with the melodious sounding name of Tangelo Park.

A quick snap from the city’s tourist engine, this neighborhood of small, once-charming houses seemed a world away from theme park pleasures as its leaders tried to beat back drugs, crime and too many shuttered homes. Nearly half its students had dropped out of school.

Twenty-one years later, with an infusion of $11 million of Mr. Rosen’s money so far, Tangelo Park is a striking success story. Nearly all its seniors graduate from high school, and most go on to college on full scholarships Mr. Rosen has financed.

Young children head for kindergarten primed for learning, or already reading, because of the free day care centers and a prekindergarten program Mr. Rosen provides. Property values have climbed. Houses and lawns, with few exceptions, are welcoming. Crime has plummeted.