This paper assesses the relationship between participation in two tertiary science courses and the science teaching efficacy beliefs (STEBs) of one cohort of preservice elementary teachers over a four-year period. Two Type II case studies were conducted within the courses. Data were collected through 26 administrations of the Science Teaching Efficacy Belief Instrument-B and semi structured interviews. Results showed that participation in the subjects covaried with increases in the participants' STEBs. These increases in STEBs remained durable for two years. Implications for these findings are discussed within the paper.