Summary.Four Piagetian formal thought tasks, three formal operational reasoning tests, and a test of verbal intelligence were administered to 90 scholastically above‐average adolescents, 30 at each of three age levels (13, 16 and 19). The formal reasoning tests provided scores indicating level of formal reasoning in each of three content areas—biology, history and literature, respectively. It was hypothesised that formal operational skills are unifactor. With the use of maximum likelihood factor analysis it was determined that the eight measures had a bifactor structure with a large general factor and a secondary factor which distinguished tasks from tests. Also formal thought was found to have a substantial verbal intelligence component as well as non‐verbal intelligence compo