This study examines the influence of personality traits, goal orientation and self-efficacy on high school teachers' participation in learning activities in the workplace (i.e. experimentation, informal interaction with colleagues, self-regulation and avoidance behaviour). A convenience sample of 95 teachers from six high schools in Flanders (Belgium) participated in this exploratory study. They completed a questionnaire consisting of different instruments to map their personality (NEO-FFI), goal orientation (adaptation of Achievement Goal Questionnaire), self-efficacy (Teachers' Sense of Efficacy Scale) and participation in learning activities (adaptations from different scales). Results of multivariate regression analyses indicate that conscientiousness, extraversion and openness have a positive effect on teachers' participation in learning activities in the workplace. However, learning orientation and self-efficacy are found to be better predictors for participation in experimentation, informal interaction and selfregulation. Analysis using structural equation modeling reveals an indirect relationship between extraversion and self-regulation, mediated by self-efficacy. Learning orientation mediates the impact of conscientiousness on informal interaction. As teachers' goal orientation and self-efficacy can be influenced, school policy makers should reflect upon ways on how teachers' goal orientation and self-efficacy can further be enhanced.