This paper provides a theory of firm behavior motivated by moral duty, self-interest, and social pressure. A morally managed and a self-interested firm compete in a market in which their corporate social performance (CSP) provides product differentiation. Some citizens have altruistic or warm glow preferences for products with associated CSP, personal giving to social causes, holding shares in firms providing CSP, and contributing to social pressure to increase CSP. Social pressure is delivered by an activist NGO funded by voluntary contributions by citizens. The model characterizes an equilibrium in the product market, the capital market, and the market for social pressure. The equilibrium establishes a price for CSP and for activist-induced social pressure. The theory provides predictions of the market values of firms, the prices of products, firm profits, target selection, contributions to the activist, and the amount of CSP supplied. For example, if citizens do not distinguish between morally motivated CSP and CSP induced by social pressure, the activist is more likely to target the softer, morally motivated firm. Higher quality activists are better funded, target self-interested firms, and obtain greater corporate social performance. Lower quality activists target morally managed firms.