This study investigated how teachers' professional learning is influenced by their implicit goals and beliefs. A path model that attempts to explain variation in teachers' professional learning was tested. A new variable, teacher mindset, was developed to operationalize teachers' conceptions about teaching ability. The model explores how teacher mindset, teacher efficacy, and goal orientation interact to predict teachers' participation in professional learning. 312 teachers participated in the study. The path analyses provided strong support for the model. Both in regression and path analyses, teacher mindset emerged as a significant predictor. The findings suggest that teacher improvement may depend on the variables highlighted in this study, most notably teacher mindset. Implications for teacher education, professional development, and policy are discussed.