The humanistic concept of flow (Csikszentmihalyi, 1975), which describes intrinsically enjoyable experiences, is based on the ratio of challenges to skills. Csikszentmihalyi's (1975) flow theory emphasises the positive affective state ('flow') experienced where challenges and skills are matched, so that the theory has clear implications for the study of personality. However, of more immediate consequence are the possible implications of the experience of flow and intrinsic motivation for the study of of health and well-being. In this study, three experiments were conducted. The first determined the intrinsically motivating qualities of performing on a computer video game in comparison with other stimulating and unstimulating activities. Subsequently, this task was used in Experiment Two to formally examine the flow theory by assessing skill, and varying the challenge dimension of the activity. Affective states were assessed via the Experience Sampling Method (Larson and Csikszentmihalyi, 1983) and Experience Questionnaire (Privette, 1984) thereby identifying the factors underlying the flow experience. Three factors, labelled intensity of flow, coping and motivation, were shown to vary in line with predictions from the flow model; that is to say, the flow and experience factors were at their most positive where skill and challenge were matched, and at their most negative where the skill/challenge ratio imbalance was greatest. Experiment Three originated the construction of 'flow profiles' to examine the hypothesis that the flow experience is a desirable quantity, and that differences in individual experiences of flow are accompanied by crucial differences in personality factors. The findings suggested that differences in flow experiences should not be considered in personality terms alone, but also that the flow experience is associated with more desirable personality characteristics from a health point of view, as described by Eysenck (1987). More specifically, healthy personality characteristics were associated with positive aspects of the flow factors (intense flow experience, ability to cope, motivation), whilst vulnerability to stress related disease was associated with the negative aspects of the flow factors (less intense flow experience, coping at a cost to health, less motivation). Evidence as to the causality of the relationship between flow, personality and health is discussed, and it is concluded that this indicates a cyclical relationship. It was concluded that the flow experience may therefore play an important role in the prevention of stress related health disorders via it's interaction with personality factors. Further implications and directions for future research are discussed.