BACKGROUND: Contemporary views on motivation suggest that the approach-avoidance achievement goals conceptualization--namely the trichotomous model--can shed light on the important issue of student motivation. AIMS: To test the predictive value of the trichotomous model on the investment in learning a sport task for test preparation, and to validate a model which included a set of psychological processes (i.e., state anxiety and competence valuation) which mediate the relationship between the three goals (i.e., performance-approach, performance-avoidance, and mastery goals) and test preparation. The study was designed to investigate the direct and mediational effects of three experimental goal conditions on the time in which pupils prepared for a sport test. SAMPLE: French male school pupils (N = 75). Pupils were aged 13-15 years and attended schools in southern France. METHOD: Pupils prepared themselves for a sport task with a 5-minute period of training, and performed in one of three experimental conditions to which they were randomly assigned: a performance goal with a positive outcome focus (performance-approach), a performance goal with a negative outcome focus (performance-avoidance), or a mastery goal. RESULTS: Pupils in the performance-avoidance group reported higher state anxiety and lower competence valuation than those in the performance-approach and mastery groups, and this psychological state was associated with less time taken to prepare for the test. CONCLUSION: School pupils placed in an examination preparation context that elicits a performance goal with a negative outcome focus (performance-avoidance) show motivational deficits which manifest themselves in less time spent practising. The trichotomous model appears to be valid for the study of motivational processes in school physical education.