Several studies have found learning of biconditional grammars only under intentional rule-search conditions (e.g., Johnstone & Shanks, 2001). Memorization of strings merely led to the learning of chunks. We used a musical grammar, a diatonic inversion, that is a type of biconditional grammar. Participants either were required to memorize a set of grammatical tunes (incidental learning), or were asked to search for the underlying rule whilst being given feedback about their performance (intentional learning). The results showed that participants in the incidental-learning condition did not learn the inversion rule and merely acquired explicit knowledge about chunks. However, participants in the intentional-learning condition learnt both the inversion rule and chunks.