In the critical transition from university student to full-time teacher that occurs during student teaching, preservice teachers can request assistance from mentors. Yet, some preservice teachers rarely ask for help. To understand when and why preservice teachers seek help, a self-regulated learning framework was used to measure and evaluate connections between perceived mentor support, self-efficacy, and help-seeking. Recognizing that help-seeking changes over time, a sample of preservice teachers (N = 130) reported on their experiences before, during, and after student teaching. Self-efficacy was associated with help-seeking regardless of mentor support perceptions. The longitudinal nature of this study extended previous research findings by verifying the predictions of the inverted U-curve hypothesis over time, confirming that help-seeking becomes more frequent when self-efficacy becomes more moderate. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]