Across the Global South, adolescent girls are victims of intersecting gender-based discrimination that limits their educational opportunities and exposes them to child marriage, teen pregnancy and female genital mutilation (FGM). This paper presents a case study of an innovative program to support adolescent girls’ rights and development in southern Senegal. Implemented in 90 rural and urban sites, Girls’ Holistic Development (GHD) is a community intervention developed through a multi-year action-research approach, that is: culturally-grounded; intergenerational; builds on existing community assets; elicits dialogue for consensus-building for change; and strengthens community leaders’ capacity to catalyze change in social norms affecting girls. Extensive research on  GHD, using both quantitative and qualitative methods, supports the conclusion that GHD has contributed: to changing community norms and practices regarding girls’ education, child marriage, teen pregnancy and FGM; and to modifying gender-biased attitudes negatively affecting girls. Other significant outcomes of GHD include: creation of local alliances of girls, mothers and grandmothers; and empowerment of grandmother leaders, both promoting GHD.  The GHD intervention responds to calls from the Global South to decolonize development programs through adoption of social change strategies that respect and build on extant cultural values, roles and traditions.