Dutch nouns are divided into two groups according to grammatical gender which is, among others, marked on the definite determiner: common nouns take the definite determiner de and neuter nouns take the definite determiner het. This study is unique in systematically investigating the acquisition of grammatical gender and the definite determiner in the production and knowledge data of the same Dutch children. Three groups of children were examined: (i) typically developing monolinguals (L1-TD: 6; 7-9; 11), (ii) monolinguals with Specific Language Impairment (L1-SLI: 8; 4-12; 0), and (iii) typically developing bilinguals, who are early second language learners (eL2: 6; 7-10; 0). The three groups of children reveal different stages in discovering that de and het cover the gender paradigm. At comparable ages, the L1-TD children have completed this paradigm discovery; however, the eL2 children have not yet completed it, and the L1-SLI children are only at the first stage of the discovery of the gender paradigm.