The important role of self-efficacy (SE) in students' motivation, engagement, persistence, and academic achievements has been reconfirmed by ample research, both in general and for STEM disciplines. As most studies focused on traditional school systems, additional research is needed on how science SE develops in different educational environments, which was the goal of this study. Data were collected from 1979 students in Grades 5-9 from 19 traditional, Waldorf, and democratic schools in Israel. Students completed a questionnaire that assessed their science self-efficacy (SSE), general and academic self-efficacy (GASE), and the sources of their SSE: teachers', parents', and peers' social persuasions, vicarious experiences and mastery experiences. Results revealed that SSE and GASE differed in their levels and in the way they changed with grade. These differences, and variations in the roles of the various sources of SSE, appeared to be influenced by the schools' cultures and curricula. Quantitative results are accompanied by verbal illustrative examples from interviews with students and teachers.