Keywords: Adolescents (13-19 years), Behaviour Modification (e.g., provision of item/tool, incentives, goal setting), Community, Education / Awareness & Skill Development / Training, Grade school aged (5-12 years), Home, Infants (0-1 years), Internet, Mail, Meta-analysis, Obesity, Phone, Physical Activity, Preschool aged (1-4 years), School, Social Support (e.g., counseling, case management, outreach programs) , Youth Health