This article describes the results of three pilot studies that were conducted to evaluate the recently developed "Strong Kids" and "Strong Teens" social-emotional learning programs in increasing students' knowledge of healthy social-emotional behavior and decreasing their symptoms of negative affect and emotional distress. The first study included 120 middle school students (in grade 5) from a general education student population. The second study included 65 general education students in grades 7-8. The third study included 14 high school students (grades 9-12) from a regional special education high school, who were identified as having emotional disturbance. The three groups participated in either the "Strong Kids" (groups 1 and 2) or "Strong Teens" (group 3) programs, receiving one-hour lessons and associated assignments once a week for 12 weeks. Social-emotional knowledge and negative emotional symptoms of participants were assessed using brief self-report measures, in pretest-posttest intervention designs. All three studies showed that, following participation in the respective programs, students evidenced statistically significant and clinically meaningful changes in desired directions on the target variables. Implications for future research are discussed, as is the importance of social and emotional learning as a prevention and intervention strategy to promote mental health among students in schools. (Contains 1 table.)