Purpose: The authors tested associations between (a) parent-reported temporary vs. persistent vocabulary delay and (b) parent-reported behavioral/emotional problems in a sample of 5,497 young Dutch children participating in a prospective population-based study. Method: Mothers completed the MacArthur Communicative Development Inventory-Netherlands (Zink & Lejaegere, 2003) at age 18 months and the Language Development Survey (Rescorla, 1989) at age 30 months, with expressive vocabulary delay defined as scores in the lowest 15th age-and gender-specific percentiles. The Child Behavior Checklist (Achenbach & Rescorla, 2000) was completed by mothers when their children were age 18 months and by both parents when their children were age 36 months, from which Internalizing Problems and Externalizing Problems scores were analyzed. Results: All analyses were adjusted for covariates. Expressive vocabulary delay at age 18 months was weakly related to Internalizing Problems scores at age 18 months as well as mother-reported Externalizing and Internalizing Problems scores at age 36 months (the latter for boys only). Expressive vocabulary delay at age 30 months was weakly associated with mother-reported Externalizing and Internalizing Problems scores (the latter for boys only) and father-reported Internalizing Problems scores. Persistent expressive vocabulary delay predicted the highest risk of mother-reported internalizing and externalizing problems at age 36 months. Conclusion: This population-based study showed modest associations between vocabulary delay and behavioral/emotional problems detectable from 18 months onward.