The existing literature on the relationship between property rights in land and agricultural investment in Africa has given results that are often confusing and contradictory. I make two clarifying contributions to this literature. First, I pull together existing studies and investigate whether the results they find have been affected by research methods or local contexts. Studies with small sample sizes, those that use binary investment measures, and those that control for household fixed effects are less likely to find a statistically significant link between land tenure and investment. Self-reported tenure security has been a poor predictor of investment outcomes. Second, I test for a relationship between land tenure and agricultural investment in nine data sets from West Africa. While the link between tenure and investment is significant for fallow and tree planting, it is less robust for labor use and other inputs, such as manure or chemical fertilizer.