Although technology is a major driver of many of society's comforts, conveniences, and advances, it has been responsible, in a significant way, for engineering regular physical activity and a number of other positive health behaviors out of people's daily lives. A key question concerns how to harness information and communication technologies to bring about positive changes in the health promotion field. One such approach involves community-engaged “citizen science,” in which local residents leverage the potential of information and communication technologies to foster data-driven consensus-building and mobilization efforts that advance physical activity at the individual, social, built environment, and policy levels. The history of citizen science in the research arena is briefly described, and an evidence-based method that embeds citizen science in a multilevel, multisectoral community-based participatory research framework for physical activity promotion is presented. Several examples of this citizen science-driven community engagement framework for promoting active lifestyles, called “Our Voice,” are discussed, including pilot projects from diverse communities in the United States as well as internationally. The opportunities and challenges involved in leveraging citizen science activities as part of a broader population approach to promoting regular physical activity are explored. The strategic engagement of citizen scientists from sociodemographically diverse communities across the globe as both assessment as well as change agents provides a promising, potentially low-cost, and scalable strategy for creating more active, healthful, and equitable neighborhoods and communities worldwide.