The Experience Sampling Method was employed to collect data from a sample of 35 sixth-form college students over a period of one week. This methodology involved the subjects answering questions printed in a diary on receipt of signals from a pre-programmed watch. They also completed a package of questionnaires related to psychological well-being. The aim of the study was to investigate whether the experience of situations where high challenge is matched by skill (termed ‘flow’) can be classed as ‘optimal experience’. The results showed that the positive poles of subjective experience tended to cluster in ‘control’ (skills exceeding moderate challenge) rather than flow. However, more optimal experience (considered as high enjoyment) occurred in flow than expected. In addition, optimal experience in flow was characterized by high cognitive involvement. Subjects who experienced flow as optimal experience were found to score significantly higher on measures of psychological well-being than those who did not experience flow as highly enjoyable. The implications are discussed with respect to college students' quality of life and educational experiences.