Intermediate to advanced college-level L2 English learners appear to identify unknown idioms with well-known components at a notably slower pace than unfamiliar words. In addition, their definitions of idioms qualified as familiar tend to be notably less acceptable than those of words qualified as familiar. If this pattern recurs over time, the chances for learning these idioms casually might be lowered. It is argued that learners' continued awareness of the common presence of these idioms in language, is crucial to their permanent acquisition.