Motivational research in academic subjects has demonstrated that when students are interested in an activity and feel free to choose whether or not to do it, they are more likely to engage in higher-level cognitive functioning, find it easier to concentrate, persevere, and enjoy their learning. This case study of a young beginning clarinettist named Clarissa consisted of interviews and computer analysis of videotaped practice sessions. Clarissa's practice behaviour in teacher-assigned repertoire was compared with her work on a piece she chose to learn herself. Results show that when practising self-selected repertoire, Clarissa was more likely to engage in strategies that are typical at more advanced stages of development, such as silent fingering, silent thinking and singing. She also spent more time practising the piece, and persevered when faced with difficulties. Implications for instrumental pedagogy are discussed.