Using the approach of Pettengill et al. (1995), we analyze the un-conditional versus conditional cross-sectional CAPM relationship between portfolio beta-risk and return in the Argentinean, Brazilian, Chilean, and Mexican stock markets. We develop extensions to the original model to control for extra risk factors documented in the empirical literature: size, book-to-market ratio and momentum. The paper also presents the first testing of the market integration hypothesis among the Latin American stock markets. The results show that the conditional CAPM is a dominant approach even after controlling for risk factors different from beta. Statistically significant asymmetries are found, however, in the beta-risk premium between up and down markets. Additional findings suggest that the degree of stock market integration among Latin American markets falls during downturns