Headed the family company that produced middle-income housing in and around New York City more plentifully than any other builder in the years since World War II. Mr. LeFrak led the Lefrak Organization, founded by his grandfather, Aaron, in 1905. Starting with five-story walk-ups in the Williamsburg section of Brooklyn, the company put up some 200,000 houses and apartments in the metropolitan area. While Sam LeFrak was in charge, during the great wave of postwar construction and through the 1970's and 80's, about three-quarters of the total was built. Samuel Jayson LeFrak was born on Feb. 12, 1918, in Manhattan to Harry and Sarah Schwartz Lefrak. In an interview in 1995, he gave an explanation for why he spelled and pronounced his name differently from other members of his family. He said that his father, Harry, Americanized the name after arriving in the country in 1904 from France, spelling it Lefrak and pronouncing it LEH-frack. Mr. LeFrak attended Erasmus Hall High School in Flatbush and the University of Maryland. Later he studied finance at Columbia University and the Harvard Business School. Maurice LeFrak, the father of Aaron, the patriarch of the family business in New York, had been a developer in France in the 1840's. Aaron's son, Harry, first went into the glass business, designing and manufacturing customized glass for Louis Comfort Tiffany. When Mr. LeFrak started working for the family company full time in 1940 it was building Army camps and housing. His father, who had bought a 2,000-acre farm in Brooklyn in the 1920's and had been building there long before World War II, turned the presidency of the company over to him in 1948. He held it until 1975, when his son, Richard LeFrak, became president, with Mr. LeFrak holding the title of chairman. In his later years, Mr. LeFrak turned to other business ventures: oil and gas exploration through the Lefrak Oil and Gas Organization, a drilling company, and the entertainment business, through Lefrak Entertainment Company, which develops and produces popular records and buys and leases out the performance rights to popular songs. He also built a formidable art collection, which included paintings by Delacroix, Daumier, Renoir, Monet, Picasso, Pissarro and others. He was also a major philanthropist and the landscape is dotted with his endowed buildings that are named for him and his wife, the former Ethel Stone, whom he married in 1941. They include a concert hall at Queens College; a gymnasium at Amherst College; a meadow in Flushing, a sculpture terrace and art gallery at the Guggenheim Museum, a learning center at Temple Emanu-El, and a classroom building with an amphitheater at the University of Maryland. In addition to his wife and son Richard, Mr. LeFrak is survived by three daughters, Denise LeFrak Calicchio, Francine LeFrak Friedberg and Jacqueline LeFrak Kosinski, five grandchildren and two great-grandchildren.