Aim: General developmental outcome is known to be good in school-aged children who experienced febrile seizures. We examined cognitive and behavioural outcomes in preschool children with febrile seizures, including language and executive functioning outcomes. Method: This work was performed in the Generation R Study, a population-based cohort study in Rotterdam from early fetal life onwards. Information about the occurrence of febrile seizures was collected by questionnaires at the ages of 1, 2, and 3 years. At the age of 3 years, behaviour and emotion were assessed using the Child Behavior Checklist. Information on expressive language development was obtained by the Language Development Survey at the age of 2 years 6 months. To assess executive functioning, parents completed the Behaviour Rating Inventory of Executive Function--Preschool Version when their children were 4 years old. Final analyses were based on 3157 children. Results: No associations were found between febrile seizures and the risk of behavioural problems or executive functioning. In contrast to single febrile seizures, recurrent febrile seizures were significantly associated with an increased risk of delayed vocabulary development (odds ratio 3.22, [95% confidence interval 1.30-7.94]). Interpretation: Febrile seizures are not associated with problem behaviour or executive functioning in preschool children, but the results suggest that children with recurrent febrile seizures might be at risk for delayed language development. (Contains 3 tables.)