Recently, much importance has been placed on early science education. This study examined the associations between kindergarten teachers' science teaching self-efficacy, outcome expectations, and their integration of science into teaching, and investigated how four potential factors (i.e. mastery experience, interpersonal support, previous science learning experience, and perceptions of the importance of science) predict kindergarten teachers' self-efficacy and outcome expectations for science teaching. Structural equation modeling was employed to analyze questionnaire data collected from 813 teachers in public and private kindergartens (teaching children aged 4-6). The results confirmed the association between teachers' self-efficacy and their outcome expectations. When both self-efficacy and outcome expectations were taken into account to predict the degree of science integration into teaching, only science teaching self-efficacy was significantly influential. Moreover, this study revealed that all four factors were significantly associated with teachers' science teaching self-efficacy, of which mastery experience was the most potent. On the other hand, only teachers' perceptions of the importance of science and the interpersonal support they received played a significant role in directly predicting their science teaching outcome expectations. The results could shed light on how to better prepare and support early childhood teachers to integrate science into their classroom teaching.