ObjectiveInvestigate the association between the dietary diversity of preschool children and proximate factors including household food insecurity, maternal food choice, preferences, khat use, and levels of depressive symptoms.DesignCross-sectional survey of randomly selected households.SettingHaramaya Health and Demographic Surveillance site in Eastern Ethiopia, predominantly smallholder farming households.Participants678 preschool children (24–59 months) and their mothers.MethodsThe key outcome, the adequacy of dietary diversity of preschool children, was calculated using a 24-hour parental dietary recall. Binary logistic regression was then used to identify maternal and household factors associated with dietary adequacy versus inadequacy.ResultsThe majority (80.53%) of surveyed children had low dietary diversity (mean Dietary Diversity (MDD)) score of 3.06±1.70 on a 7-point scale). Approximately 80% of households exhibited food insecurity. Households with greater food security (adjusted OR (AOR)=1.96, 95% CI 1.19 to 3.23), healthier maternal food choice (AOR=2.19, 95% CI 1.12 to 4.31) and broader maternal food preferences (AOR=4.95, 95% CI 1.11 to 21.95) were all associated with higher dietary diversity of their preschool children (p≤0.05). Other covariates associated with adequate child dietary diversity included improved household drinking water sources (AOR=1.84, 95% CI 1.16 to 2.92) and family planning use (AOR=1.69, 95% CI 1.00 to 2.86). Despite predictions, however, maternal depression and khat consumption were not identified as factors.ConclusionsThe dietary diversity of preschool children is extremely low—a pattern observed in both food-secure and food-insecure households. Key factors include maternal selection of food for convenience and ease, preferences that do not include animal protein or healthier food choices, and lack of access to improved drinking water sources. Interventions around maternal food choice and preferences could improve preschool children’s nutritional health.