Prevention of childhood obesity is a national priority. Parents influence young children's healthy lifestyles, so it is paradoxical that obesity interventions focus primarily on children. Evidence and theory suggest that including parents in interventions offers promise for effective childhood obesity prevention. This case study engaged parents' as co-researchers in the design, implementation and evaluation of an intervention for low-income families with a child enrolled in Head Start. Parent engagement mechanisms include: (1) targeted partnership development (2) operationalizing a Community Advisory Board (CAB) that was the key decision making body; (3) a majority of CAB members were parents who were positioned as experts, and (4) addressing structural barriers to parent participation. Lessons learned are provided for future research, and practice.