Positive psychology interventions in educational settings aim to build positive feelings, behaviors, and cognitions among students (Waters, 2011). To ensure positive interventions produce meaningful changes, it is essential to evaluate their effectiveness. The current workshop introduces program evaluation as a tool for practitioners to systematically think through and assess the effectiveness of positive interventions. We focus on theory-driven evaluation, a method that highlights the importance of using both social science and program theories to understand mechanisms of change that lead to program outcomes (Chen, 2012; Donaldson, 2003). It allows us to ask not only whether the intervention works, but what works for whom and under what conditions. Expert evaluators will present a specific tool called “theory of change” to show how evaluation can influence program design, implementation, and outcomes. It is usually presented in graphical diagram that specifies relationships among programmatic actions, outcomes, and other contextual factors. Based on the presenters’ extensive experience teaching and practicing program evaluation science, we use lecture and interactive activities to help participants (1) gain a theoretical understanding of evaluation science and theory-driven evaluation, and (2) learn practical skills to create and use theory of change to understand, implement, and assess positive psychology interventions better.