Suppose that you read about a low-cost, evidence-based program that boosts overall school achievement by 11 percentile points while improving school climate, student behavior, and teacher satisfaction? You might be somewhat skeptical, but you'd likely be intrigued. Such an approach exists, writes school psychologist John E. Desrochers: comprehensive, schoolwide mental health programs. To be effective, schoolwide mental health programs should include a multi-tiered system of supports: (1) a solid base of services for all students; (2) targeted small-group programs for at-risk students, and (3) intensive services for students who have significant needs. The first tier is the foundation of the program, and in this article, Desrochers describes how one school (Long Lots Elementary) and its district (Westport School District) have built a comprehensive, proactive support system to improve the mental health of all students. The program, designed and implemented almost entirely by in-house staff, includes Responsive Classroom (the one externally developed component); a social skills curriculum; group meetings for all students with the school psychologist (about six times a year); whole-school meetings on social and emotional concerns; parent education groups; staff development; and transition support for students moving to middle school.