Attention problems are likely to hinder children in acquiring knowledge of their own and others’ emotions. Children with little knowledge of emotions tend to have difficulties with representing emotions, interpreting them, and sharing them, so that they are likely to spend more time in making sense of them and may thus appear to be inattentive. In order to disentangle the direction of effects between emotion knowledge and attention problems, 576 four- to- six-year-olds were interviewed at T1 and about 12 months later (T2) about their emotion knowledge. Their kindergarten teachers rated their attention problems, and their conduct problems at T1 and T2. A cross-lagged panel model indicates that children’s emotion knowledge at T1 contributed to the explanation of their attention problems at T2, after language ability and attention problems at T1 were controlled. The other cross-path from attention problems (T1) to emotion knowledge (T2) was not significant. Adding gender, behavioral self-regulation, working memory, conduct problems, or SES as alternative explanations by third variables did not alter this direction of effects. How emotion knowledge impinges on attention problems is discussed.