Crop diversity conservation in situ is an ecosystem service with benefits at household, community, and global scales. These include risk reduction and adaptation to changing physical and sociocultural environments—both important given the accelerating changes in climate, human migration, and the industrialization of agriculture. In situ conservation typically occurs as part of small-scale, traditionally based agriculture and can support cultural identity and values. Although decisions regarding crop diversity occur at the household level, few data detail the household context of in situ crop diversity management. Our research addressed this data gap for maize and Phaseolus bean in Oaxaca, Mexico, a major center of diversity for those crops. We defined diversity as farmer-named varieties and interviewed 400 farming households across eight communities in two contrasting socioecological regions. Our research asked, “In a major center of maize and Phaseolus diversity, what are the demographic, production, and consumption characteristics of the households that are stewarding this diversity?” We describe the context of conservation and its variation within and between communities and regions and significant associations between diversity and various independent variables, including direct maize consumption, region, and marketing of crops. These results provide a benchmark for communities to understand and strengthen their maize and bean systems in ways they value and for scientists to support those communities in dynamically stewarding locally and globally significant diversity.