This mixed methods study was conducted to investigate mathematics preservice teachers' (PTs) promotion of self-regulated learning (PSRL) with respect to time through participation in a self-regulated learning (SRL) enriched seminar course. PTs' self-efficacy beliefs for promotion of self-regulation (SE-PSRL) over time was also investigated. Forty-four PTs participated in the study. They were divided into two sections and the SRL enriched seminar course was implemented with the experimental group for one academic term. The control group followed a parallel course without a particular focus on SRL. Participants were administered two different scales that measured their SE-PSRL and PSRL four times during the semester. Qualitative data were also gathered through semi-structured interviews with 9 participants. Mixed design analysis of variance (ANOVA) were conducted separately for SE-PSRL and PSRL scores to investigate the differences between the groups with respect to time. Results of the study indicated that while participants' SE-PSRL scores differed statistically (F(3,126) = 9.13, p = 0.00, [eta squared] = 0.18), PSRL scores did not differ according to time and group (F(3,126) = 0.20, p = 0.90, [eta squared] = 0.01). The results from the quantitative analyses did not exactly conform with the hypotheses and interview data pointed towards various reasons for such unanticipated findings.