This paper describes a program of brief, universal, positive psychology-based interventions to increase targeted behaviors that enhance family relationships, developed and delivered to over 1500 participants using a community-based participa- tory approach. The cluster-randomized design combined interventions based on one of three themes (gratitude, hope, or open-mindedness) in one of two structures (intervention, or intervention with planning). The latter structure supple- mented with materials and exercises derived from the Health Action Process Approach model of behavior change. Plan- ning was more effective in increasing attitude and intention to perform behaviors, frequency of the targeted behaviors, and family health and happiness (Cohen ’ s d s: 0.10 – 0.16, p < 0.05), particularly in the theme targeting open-mindedness. Qualitative data supported effectiveness. This project was a fi rst effort to develop a large-scale preventive psychological intervention in an understudied culture with the goal of maximizing acceptability and utilization by involving community stakeholders in every stage of the design.