If the declines in interest and performance within school science are to be reversed, it is imperative that competent and confident teachers deliver quality science experiences. This paper reports on the long-term implementation of two complementary, student-centered tertiary science methods courses that integrated instruction in content with teaching methods within a preservice elementary teaching degree. The Science Teaching Efficacy Belief Instrument B was employed to collect data from multiple cohorts (2007-2014). Multiple iterations of the quasi-experimental design were employed. Complete data supplied by 234 preservice teachers were analyzed using MANOVA with repeated measures on the occasion of testing. Results indicate that personal and outcome efficacy beliefs grew significantly with moderate to large effect sizes, in ways that are atypical within the literature. Broader implications are discussed.