JEL classification numbers: G11, G14, G15 We empirically examine stock price index data for eight developed and ten emerging markets from 1970 to 1997. There were nine stock market crises over our sample period, three each in the developed stock markets, the Asian stock markets and the Latin American stock markets. We find important differences in the characteristics of stock market crises between the developed and emerging stock markets. While each developed market crisis has been less severe than the previous one, both in terms of the extent of price decline and the duration of the crises, this is not so for the emerging stock markets. For emerging markets stock crises, prices tend to fall rapidly and steeply, but take longer to recover, in about three years on average. For both developed and emerging markets, prices fall for at least three years subsequent to recovery from a crisis. All the crises we study are associated with contagion---i.e ., most individual markets in a region are in crisis when the regional market is also in crisis. Finally, for U.S. investors with long investment horizons (six months or more), international stocks continue to provide diversification benefits even during times of market crises.