The perception of self-efficacy introduced by Albert Bandura's social cognitive theory is defined as a person's view of their capacity to organize and carry out the activities necessary for success in a specific situation. The most effective mathematics teachers believe that they are a capable and important influence on their students' understanding of mathematics, which is known as having a high self-efficacy for teaching mathematics. As efficacy for teaching is more difficult to change after the teacher enters the classroom, attending to preservice teachers' mathematics self-efficacy is worthy of examination within the teacher preparation program. The purpose of this study was to determine elementary and early childhood preservice teachers' self-efficacy beliefs related to teaching mathematics. Elementary and early childhood preservice teachers' (n = 203) mathematics teaching efficacy beliefs, including personal mathematics teaching efficacy and mathematics teaching outcome expectations, were measured at the beginning of the semester prior to internship. Responses indicated that participants had strong personal mathematics teaching efficacy but only modest expectations of their ability to positively influence students' mathematical learning. Implications for practice and future research are shared.