Thornton Tomasetti (formerly The Thornton-Tomasetti Group, Thornton Tomasetti Engineers, LZA Technology) is an American 1,200+ person structural engineering consulting firm headquartered in New York City. Founded in 1956 as Lev Zetlin & Associates, the 50-year-old company has office locations throughout the world. Thornton Tomasetti works to advance sustainable design and construction practices. About one-fifth of its staff are LEED accredited professionals (LEED AP). Thornton Tomasetti was the first structural engineering company to sign the AIA 2030 Commitment.