This study aimed to understand the relationship among conceptions of teaching and learning (COLT), classroom management self-efficacy (CMSE), and pedagogical content knowledge self-efficacy (PCKSE). A total of 485 in-service Taiwanese preschool teachers participating in this study completed three questionnaires, viz. the Conceptions of Teaching and Learning, the Classroom Management Self-efficacy, and the Pedagogical Content Knowledge Self-efficacy. The research findings indicated that, while teachers regarded conceptions of teaching and learning from a constructivist perspective, they tended to possess higher classroom management self-efficacy and in turn expressed higher PCK self-efficacy. On the contrary, teachers with traditional conceptions of teaching and learning tended to have lower classroom management self-efficacy and accordingly displayed lower PCK self-efficacy. According to the research findings, the present study encouraged teachers to develop constructivist COTL in order to foster better management and PCK. Besides, it is suggested that future studies explore other factors affecting teachers' self-efficacy.