Our specific aim was to characterize maternal knowledge of anemia and its relationship to maternal and child anemia and to behaviors related to anemia reduction. We examined the relationship between maternal knowledge of anemia and anemia in the mother and the youngest child, aged 6-59 months, in 7,913 families from urban slums and 37,874 families from rural areas of Indonesia. Knowledge of anemia was defined based upon the mother's ability to correctly name at least one symptom of anemia and at least one treatment or strategy for reducing anemia. Hemoglobin was measured in both the mother and the child. In urban and rural areas, respectively, 35.8 and 36.9% of mothers had knowledge of anemia, 28.7 and 25.1% of mothers were anemic (hemoglobin <12 g/dL), and 62.3 and 54.0% of children were anemic (hemoglobin <11 g/dL). Maternal knowledge of anemia was associated with child anemia in urban and rural areas, respectively (odds ratio [OR] 0.90, 95% confidence interval [CI] 0.79, 1.02, P = 0.10; OR 0.93, 95% CI 0.87, 0.98, P = 0.01) in multivariate logistic regression models adjusting for potential confounders. There was no significant association between maternal knowledge of anemia and maternal anemia. Maternal knowledge of anemia was significantly associated with iron supplementation during pregnancy and child consumption of fortified milk. There was no association of maternal knowledge of anemia with child deworming. Maternal knowledge of anemia is associated with lower odds of anemia in children and with some health behaviors related to reducing anemia.