The main purpose of this study was to explore the effects of two college-level mathematics courses on preservice elementary teachers' mathematics anxiety and mathematics teaching self-efficacy beliefs. For this purpose, a quasi-experimental study was implemented on two college-level mandatory mathematics teaching methods courses that were specifically designed based on Bandura's (1977) self-efficacy expectations theory. The findings of the study revealed a statistically significant difference between the beliefs of participants in the control and intervention groups for mathematics teaching self-efficacy after the intervention process, and a statistically significant change was found on the preservice elementary teachers' mathematics anxiety and mathematics teaching self-efficacy beliefs within the intervention group. Moreover, qualitative exploration revealed the important aspects of this change as being pedagogical and emotional transformation, in which the intervention process helped the preservice teachers to develop a positive attitude and a better understanding towards mathematics and its teaching. Creation of discussions around preservice teachers' previous mathematics related experiences and helping preservice teachers to succeed at challenging mathematical tasks could help teacher educators design more effective mathematics teaching courses on decreasing mathematics anxiety and increasing mathematics teaching self-efficacy.