We document that ownership by officers and directors of publicly traded firms is on average higher today than earlier in the century. Managerial ownership has risen from 13 percent for the universe of exchange-listed corporations in 1935, the earliest year for which such data exist, to 21 percent in 1995. We examine in detail the robustness of the increase and explore hypotheses to explain it. Higher managerial ownership has not substituted for alternative corporate governance mechanisms. Lower volatility and greater hedging opportunities associated with the development of financial markets appear to be important factors explaining the increase in managerial ownership.