The extensive literature on price momentum effects is a potential source of confusion for portfolio managers because conflicting explanations give rise to different implications for portfolio strategy. Analysis of the value-weighted large-capitalization universe represented by the MSCI World Index indicates that price momentum is driven largely by industry momentum, not individual-stock momentum, and that it is not a result of cross-sectional dispersion in industry mean returns or varying industry exposure to systematic risk. In a small-cap universe, stock-specific effects assume greater importance. For sample periods 1992–2003 and 1980–2003, value investors would have reduced risk by imposing sector neutrality on their portfolios whereas growth managers could have profited by relaxing sector constraints.