The purposes of this study are to examine: (a) the effects of a well-implemented, school-based, universal social skills intervention on time-spent in formal social skills instruction and academic instruction time in the classroom; and (b) the effects of time-spent in formal social skills instruction on student achievement. Twelve elementary schools were matched and one school of each pair was randomly assigned to the treatment. The sample included 1,724 students in 113 third, fourth, and fifth grade classrooms with low rates of social-behavioral problems. Multilevel data analyses (HLM) methods were used to investigate the school-based treatment effect of social skills programming on academic instruction time as well as the classroom-level effect of social skills instruction on student achievement. Results indicated that treatment students received significantly more formal instruction in social skills, and that the frequency of formal social skills instruction had a very small, negative effect on students' report card grades and standardized test scores when lessons were 30 minutes or less in duration. The effects were not consistent and were so small as to have little theoretical or practical significance. Research and policy implications are discussed.