San Ildefonso (săn ēlˌdəfŏnˈsō) [key], pueblo (1990 pop. 447), N central N.Mex., on the Rio Grande, established in the early 1700s. The inhabitants are Pueblo who speak a Tanoan language. The pueblo is famous for its excellent pottery and paintings, and many of its artists have won individual fame. On Jan. 23, the day of fiesta, ceremonial dances (e.g., the buffalo and Comanche dances) are performed.