In this study, we looked at the relationship between teacher behaviors, teacher beliefs, teacher self-efficacy, and teacher subject knowledge with student achievement in mathematics. Data was collected from 103 primary school teachers and 2,148 students in the UK using achievement tests, classroom observation, and questionnaires. Structural equation modeling was used to test the hypothesis that all these factors would have a direct or indirect effect, with the factors most proximal to student achievement (teacher behaviors) having the strongest direct effect while more distal factors (e.g., teacher beliefs) influencing student achievement indirectly. This hypothesis was not rejected by the data.