This study examined the effectiveness of the PATHS (Promoting Alternative Thinking Strategies) curriculum the emotional development of school-aged children. PATHS, a school-based preventive intervention model was designed to improve children's ability to discuss and understand emotions and emotion concepts. The intervention field trial included 30 classrooms in a randomized design and involved the assessment of 286 children from grades 2 and 3. Approximately 30% of the children were in self-contained special needs classrooms, with the remainder in regular education. Teachers were trained in the intervention model and provided PATHS lessons during most of the one school year. Results indicated that the intervention was effective for both low- and high-risk (special needs) children in improving their range of vocabulary and fluency in discussing emotional experiences, their efficacy beliefs regarding the management of emotions, and their developmental understanding of some aspects of emotions. In some instances, greater improvement was shown in children with higher teacher ratings of psychopathology. Discussion focused on the nature of change school-based prevention trials.