In this study we report two studies on the development and testing of a scenario-based learning (SBL) activity delivered to 191 preservice teachers in the UK and Australia. SBL uses interactive, realistic classroom scenarios, coupled with self-reflection and feedback from experienced teachers to enhance the self-efficacy and classroom readiness of preservice teachers. Findings from Study 1 indicated that participants found the activity engaging and useful, and reported a high level of agreement that the activity increased self-efficacy and preparedness for teaching placements. Findings from Study 2 revealed that most participants reported higher levels of placement self-efficacy and preparedness. A quasi-experimental design in Study 2 revealed statistically significant increases in emotional classroom readiness, but not in teaching self-efficacy, motivational classroom readiness, or cognitive classroom readiness. We conclude that an SBL activity can play an important role in preparing preservice teachers for school-based teaching placements.