Biodiversity conservation and food security are often assumed to be separate or conflicting issues. In the municipality of Tzucacab, in a rural corner of Mexico’s Yucatan peninsula, I found that crop diversity and food security are deeply intertwined. I measured food security and home garden agrobiodiversity on a randomized selection of sixty smallholder farms in the municipality, conducted ethnographic interviews over a period of four years, and collaborated with six high school students on a participatory photography project documenting local food culture. From the quantitative data, I found that crop diversity is the strongest predictor of household food security during a drought in the rural municipality I surveyed. This finding indicates that maintaining high levels of agrobiodiversity can be an important strategy for subsistence farmers to buffer their food supply against the risk of crop failure. Additionally, I found evidence that diversification of the home garden is one important strategy managing risk among a complex of several approaches to livelihood diversification. The finding helps to explain why some farmers conserve diversity while others do not, and suggests that the goals of agrobiodiversity conservation and rural food security might be better addressed together. These results point to the ability of small-scale, diverse farms run by campesino farmers to feed themselves, challenging the dominant discourse and practice of development that prioritizes increasing yields above all other properties of agroecosystems.