The view that formal instruction is important for raising learner consciousness of grammatical structures has become prominent recently. One component of this view is the critical role in language processing assigned to noticing the target structures in subsequent communicative input. The research presented here investigates the amount of learner noticing produced by two types of grammar consciousness-raising treatments designed to develop formal knowledge of problematical grammar structures: teacher-fronted grammar lessons and interactive, grammar problem-solving tasks. The frequencies of noticing the target structure in communicative input one and two weeks after the grammar consciousness-raising treatments are compared with the noticing frequencies of a control group which was not exposed to any type of grammar consciousness-raising activity. The results indicate that task performance was as effective as formal instruction in the promotion of subsequent significant amounts of noticing, as compared with the noticing produced by the control group. It is demonstrated that a number of learners who developed knowledge about grammar structures went on to notice those structures in communicative input after their consciousness had been raised.