ObjectiveThe main objective of this study was to assess the prevalence of dietary diversity and associated factors.DesignCross-sectional study.SettingLokossa district, southern Benin.ParticipantsA survey conducted in a probabilistic sample of 612 students (345 boys and 267 girls), aged 8–17 years old from 26 primary schools. Dietary Diversity Scores were calculated by summing the number of food groups consumed by the schoolchildren and adolescents over a 24-hour recall period. Adequate dietary diversity can be assigned to a consumption that is greater than or equal to five food groups, and inadequate dietary diversity can be assigned to a consumption that is lower than five food groups. Descriptive statistics such as frequency, mean and SD were computed. Statistical analysis was performed on the data to determine which variables were associated with dietary diversity as well as the results of the adjusted OR with a 95% CI. A p<0.05 was considered statistically significant.ResultsThe proportion of schoolchildren and adolescents with inadequate dietary diversity was 25.8% (95% CI 15.1% to 40.5%). Schoolchildren and adolescents living in rural areas, having low household socioeconomic status, eating breakfast less than 5 days per week and no eating school meals were significantly associated with inadequate dietary diversity.ConclusionsThe results of this study revealed that the diet among schoolchildren and adolescents lacked diversity and is associated with socioeconomic status, rural living, eating breakfast and school meals. Public health interventions, such as school meal programmes in rural and isolated areas, in association with poverty-reducing programmes and nutrition education, are recommended to improve the quality of diet and limit the consequences of poor diet diversity.