Shamiri means “thrive” in Swahili. To help youth thrive in East Africa, the aptly named Shamiri Institute develops and deploys evidence-based interventions that improve the lives of children and adolescents. By promoting gratitude, purpose and the fostering of a growth mindset, the Shamiri program seeks to improve adolescent mental health. As part of the Global Innovations for Character Development initiative, this project will evaluate the Shamiri program, a four-week intervention delivered by lay workers. In previous evaluations, Shamiri was shown to appeal to Kenyan adolescents. It also reduced depression and anxiety, while improving peer social support and academic achievement. Building on these findings, this project will undertake a rigorous evaluation of the three character strength components of the program. In doing so, it will identify the effect of each individual strength on adolescent mental health, social and academic outcomes. Led by Dr. Christine M Wasanga, the research team will conduct a randomized controlled trial based in schools. The study has four arms: gratitude, purpose, growth mindset, and active control (study skills). The target sample size is two thousand high school students recruited from low- and middle-income neighborhoods in and around Nairobi. The project is a collaboration between the Shamiri Institute, Harvard University, and the University of Pennsylvania.