The purposes of this study were to (a) assess the efficacy of a universal classroom-based mental health and social skills program for primary school students in Vietnam, and (b) given the universal nature of the intervention, assess outcomes as a function of risk status (high versus low). RECAP-VN is a semi-structured program that provides students with classroom social skills training, and teachers with in-classroom consultation on program implementation and classroom-wide behavior management. Project data were collected at three time-points across the academic year from 443 second grade students in regards to their social skills and mental health functioning, in the Vietnamese cities of Hanoi and Danang. Mental health functioning (emotional and behavioral mental health problems) was the ultimate outcome target (at Time 3), with social skills intermediate (at Time 2) outcomes targeted to improve mental health functioning. Significant treatment effects were found on both social skills and mental health functioning. However, although program effects on mental health functioning were significant for both low and high risk status groups, program effects on social skills were only significant for low risk status students, suggesting that different mechanisms may underlie program effects for high and low risk status students. Overall the results of this study, one of the first to assess directly the effects of a school-based program on mental health functioning in a low or middle income country, provide some support for the value of using school-based programs to address the substantial child mental health treatment gap found in low- and middle-income countries.