There have been many approaches to understanding contraception use including social cognition models which have been criticised for their individualistic approach and their static nature. The present quantitative study developed and refined a contextual and dynamic model of contraception use that was derived using qualitative research. This model conceptualizes the predictors of contraception use in terms of the meaning and importance of a range of social goals, perceptions of vulnerability, and constraints on or facilitators of contraception use each of which changes over time. The present study operationalized this model in relation to emergency contraception and explored differences between users and non-users and between episodes of use and non-use. In terms of users and non-users, the results showed that the users of emergency contraception showed a more positive view of an emergency contraception user, perceived greater support from their partner for emergency contraception use, rated themselves more at risk of pregnancy, and felt more confident about asking for emergency contraception. In terms of use and non-use, use was related to an increased belief about the risk of pregnancy, increased partner support, increased concern about health care professionals and the side-effects of the drug, and a more positive identity of an emergency contraception. The study has helped to develop and refine the model and has identified some key factors that are specifically relevant to emergency contraception use in a sample of women in education in and around London.