Corporations have faced a rising tide of activism by social movements over the past generation. Consumer boycotts, protests, divestment campaigns, shareholder proposals, and employee insurgencies have all become near-daily occurrences. At the same time, the range of issues that have become fair game for activism have expanded to include basic business decisions: what kinds of products to offer, which executives to appoint, whom to work with as customers and suppliers, where to locate operations, or how to engage the political system, to name just a few. But has the new wave of activism made a difference? Do social movements actually improve corporate behavior, or do they just prompt public relations efforts detached from the real activities of the business? In this essay, we consider three alternative perspectives on this question, and along the way review the ample research that has appeared on social movements and organizations over the past 20 years. Previewing where we end up: we do not reach a consensus conclusion, but we do learn a lot along the way and make several suggestions for future research that might get us closer to answering this question.