Abstract This study examines the Dutch intelligibility of a group of monolingual Dutch and bilingual Turkish-Dutch preschool children in Flanders, as rated by native Dutch listeners and measured by a Dutch intelligibility test. The intelligibility of the bilingual children is compared to that of the monolingual Dutch children, in order to examine whether age and/or task effects are similar or different in the two groups. The results revealed that intelligibility was affected by age, but showed no significant interaction between age and group. However, we found a significant interaction between age and task: children’s intelligibility increased with age for a word production as well as a sentence production task, but much more so for the latter than for the former. We discuss the results in relation to the children’s developing phonological systems, the age of exposure to Dutch and the nature of the test.