This study brings together two lines of research on teachers' affective responses toward mathematics curriculum reforms: their concerns and their efficacy beliefs. Using structural equation modeling to analyze data on 151 elementary mathematics teachers' concerns and efficacy beliefs 5 years into a mandated curriculum reform on problem solving, the study provides empirical support to a model integrating teachers' concerns and efficacy beliefs. This model suggests that teachers' concerns of preceding stages inform their concerns of succeeding stages; that teachers' efficacy beliefs about using the reform affect their task and impact concerns and are, in turn, informed by their self concerns; and that efficacy beliefs about employing pre-reform instructional approaches influence all types of teacher concerns. A qualitative analysis of data from 53 teacher logs provided additional insights into teachers' concerns about the reform. We discuss the policy and methodological implications of these findings and offer directions for future studies.