This chapter describes how social rules and institutions are understood as evolutionarily stable strategies within a cultural evolution framework, distinct from biological evolution. It posits evolutionary game theory (EGT) as a foundational logic for studying these dynamic processes. The chapter first reviews basic game theory concepts, including the Nash Equilibrium and the Prisoner’s Dilemma, explaining how elements like repeated interactions and sanctions can facilitate cooperation. It then distinguishes EGT from classical game theory, emphasising EGT’s explicitly dynamic element and more appropriate assumptions for social science, such as bounded rationality. Two main EGT approaches are detailed: the concept of evolutionarily stable strategies (ESS) and models exploring dynamic changes in strategy frequencies. A key focus is EGT’s application to the emergence of social, moral, and legal norms as successful strategies derived from individual decisions in repeated interactions. The chapter extensively describes Jason McKenzie Alexander’s agent-based models, which, by considering small, heterogeneous populations, limited interactions, ‘key agents’, and non-determinism through innovation, and provides more realistic insights into cultural evolution and norm formation. It also discusses various learning rules agents may employ. Ultimately, the chapter presents EGT as a sophisticated lens for understanding factors conditioning norm emergence and stability.