Objective Physical inactivity and poor dietary habits plague Americans as health challenges, with women of color most vulnerable to their detrimental effects. Individually focused interventions have not demonstrated lasting success, possibly due to the lack of focus on sustainable social and physical environment factors. This manuscript describes the rationale, design and methodology of Health Is Power (HIP), a transcultural, community based, randomized controlled trial that investigated the effectiveness of a group cohesion intervention to increase physical activity and improve dietary habits in African American and Hispanic or Latina women in Houston and Austin, Texas. Methods The intervention development was guided by group dynamics principles anchored within an ecologic model. Results Women participated in three health assessments and a six month face to face intervention that included evidence-based behavioral methods – integrated into strategies to promote group cohesion – framed to account for environmental factors contributing to health disparities. Women participated in team building activities, environmental mapping exercises, and supervised walks or taste tests. Conclusions Neighborhood contextual and environmental measures are described to test ecologic factors that may contribute to behavioral maintenance. Theoretically guided interventions that account for multiple levels of influence in behavior initiation and maintenance stand to improve health outcomes in vulnerable populations.