Using latent growth models, we explored: (a) The effect of middle school students’ (n=189) preintervention science self-efficacy and science interest on their initial interest in an Ecosystems Multi-User Virtual Environment (EcoMUVE) and the rate of change in their interest in EcoMUVE; and (b) the mediating effect of students’ initial interest in EcoMUVE and rate of change in interest on students’ post-intervention science self-efficacy and interest in science. Results showed that: (1) students’ pre-intervention self-efficacy for science had an effect both on students’ triggered situational interest for EcoMUVE and on students’ maintained situational interest for EcoMUVE; (2) both triggering and maintaining situational interest in EcoMUVE were important in developing students’ science self-efficacy. In fact, maintained situational interest was the stronger predictor; and (3) maintained situational interest for EcoMUVE translated into individual interest for the science content. Results support and extend social cognitive theory as well as models of interest development.