Words differ with respect to their frequency of-occurrence in the language and with respect to the age at which they are acquired Research has indicated that both variables have a large impact on the speed of processing in a multitude of psycholinguistic tasks. A problem for the research, however, is that the information about the age of acquisition for many types of words is very limited. In Dutch, the information is largely confined to short words Because there is increasing evidence that age of acquisition may be an important variable in the organisation of the semantic system, we present data about 2,332 carefully selected words from 49 different semantic categories. These will provide researchers with the information needed to test a wide range of hypotheses about the origins of the age-of-acquisition effect and to adequately select their stimuli for semantic categorisation tasks.