This chapter examines proverbs as informal institutions that help coordinate economic behavior in contexts where formal rules are limited or costly to enforce. Drawing on institutional economics, especially Douglass North’s critique of institution-free neoclassical models, it argues that proverbs function as culturally embedded heuristics that reduce transaction costs, stabilize expectations, and guide cooperation under uncertainty. Sayings such as “my word is my bond” and “pacta sunt servanda” transform promises into socially enforceable obligations, while others promote work ethics, reciprocity, and redistributive norms. The chapter also explores how proverbs shape social capital and reputational dynamics, illustrating how trust, peer influence, and collective-action problems spread through social networks. Proverbs concerning cooperation and reputation align with game theory and Ostrom’s principles of collective governance. Ultimately, the chapter presents proverbs as a form of “proverbial capital” that transmits economic knowledge, legitimizes institutions, and sustains cooperation, fairness, and reciprocity across diverse historical and cultural settings.