So far, processing studies on grammatical norm violations (GNVs) in Dutch (i.e., als ‘as’ in comparatives) have mainly focused on general differences between GNVs and their grammatical and ungrammatical counterparts. The present study is the first to also systematically investigate between-participant and between-construction variation in the processing of GNVs, using a self-paced reading task. Age and educational level were investigated as potential sources of between-participant variation, and between-construction variation was assessed by including three GNVs that vary in the amount of prescriptive attention they receive in society. Results indeed showed that the processing of GNVs was influenced by the age and educational level of participants. Moreover, different results were obtained for different norm violations. Based on these results, we conclude that it is very important to take into account differences between participants and constructions when studying the processing of GNVs.