On farm conservation of crop diversity entails policy challenges, especially when the diversity of crops maintained on farms has both inter-specific (among crops) and infra-specific (within a crop) components. Survey data is used to compare the determinants of inter- and infra-specific diversity on household farms in the highlands of northern Ethiopia. Physical features of the farm, and household characteristics such as livestock assets and the proportion of adults that are men, have large and significant effects on both the diversity among and within cereal crops grown, varying among crops. Demographic aspects such as age of household head and adult education levels affect only infra-specific diversity of cereals. Though there are no apparent trade-offs between policies that would enhance one type of diversity (richness) versus another (evenness), those designed to encourage infra-specific diversity in one cereal crop might have the opposite effect on another crop. Trade-offs between development and diversity in this resource-poor system are not evident. Market-related variables and population density have ambiguous effects. Education positively influences cereal crop diversity. Growing modern varieties of maize or wheat does not detract from the richness or evenness of these cereals on household farms.