The behavior of international stock market returns in terms of their distributional properties, serial dependence, long-memory and conditional volatility is examined. A factor analysis is employed to identify the underlying dimensions of the returns. The analysis reveals the existence of meaningful factors when these are estimated from the empirical properties of a large set of international equity indices. Furthermore, the factor scores discriminate very well the stock markets according to size and level of development. International stock markets; Serial dependence; Long-memory; Conditional volatility; Factor analysis.