Household-level panel data from a representative sample of rural households in Southern Mali describing the different sources of household income are used to examine the determinants of income diversification. A conditional fixed effects logit model is employed in the analysis to control for household-specific effects. We find evidence that poorer households have fewer opportunities in non-cropping activities such as livestock rearing and non-farm work, and hence less diversified incomes. This appears to reflect their relative lack of capital, which makes it difficult for them to diversify away from subsistence agriculture. The results also indicate that households in remote areas are less likely to participate in the non-cropping sector than their counterparts closer to local markets, while households with educated heads are more likely to participate in the non-farm sector than those with illiterate heads. The significance of entry-constraints in explaining portfolio diversification suggests that the role of government in making assets-as well as improved infrastructure-available to poorer households is still essential in promoting income diversification.