Culture is a fuzzy concept without fixed boundaries, meaning different things according to situations. To address this issue, I introduce a p-model to understand culture as a system of people, places, and practices, for a purpose such as enacting, justifying, or resisting power. People refers to population dynamics, social relations, and culture in groups. Places refers to ecological dynamics, institutional influences, and culture in contexts. Practices refers to participatory dynamics, community engagement, and culture in action. Power refers to forcing others into compliance (power-over people), controlling access to spaces (power-in places), and behaving as desired (power-to practice). I use racism to illustrate the p-model and suggest applications in theory, research, and practice in developmental sciences.