Abstract
This meta-analysis reports on the effect of professional development (PD) on K-12 in-service STEM teachers' self-efficacy. There were 18 selected empirical studies in this study. Overall, PD had a modest positive effect on self-efficacy (Hedges'g = 0.551, 95% CI [0.285, 0.704], SE = 0.107) under the random-effects model. Furthermore, the findings show that (1) participant size of PD significantly contributed to the effect size of PD; (2) training hours of PD significantly contributed to the effect size of PD; (3) PD using the Teaching Efficacy Belief Instrument or other scales of self-efficacy showed larger significant effect sizes than PD using the Teachers' Sense of Efficacy Scale. This study offers insights into the design of effective PD to improve STEM teachers' self-efficacy.