Objectives: To evaluate the effectiveness of a theory-based and culturally adapted community level behaviour change intervention to improve weaning-food preparation and handling in rural Gambia. Methods: (1) A systematic review of the literature on weaning-food hygiene interventions. (2) Mixed method formative research to identify critical control points (CCP) and motivational factors for mothers‟ behaviour on weaning-food, (3) Formulation of the weaning-food hygiene intervention including performing arts. (4) Implementation and evaluation of the intervention with a cluster randomized controlled trial (cRCT). Results: The systematic review found 4 RCTs on weaning-food hygiene interventions. Formative research prioritized 5 CCPs with 6 corrective messages and 5 motivational factors. For the intervention compared to the control arm the composite behaviour score primary outcome was 72% in the intervention versus 19% respectively (p < 0.001). Each individual behaviour was significantly improved except washing of pots dried on clean surface. There was a significant reduction of contamination of weaning-food immediately after cooking and before second feeding, of children's drinking water, of diarrhoea and respiratory symptoms reported for the past 7 days, and hospital admission for diarrhoea. Conclusion: Our public health, community level intervention for mother's hygienic preparation and handling of weaning-food was effective in rural Gambia.