In this study, we test the prediction, derived from the Critical Period Hypothesis, that a native level in L2 grammar cannot be attained by learners who start acquiring a second language after childhood. We selected 43 very advanced late learners of Dutch (native speakers of German, French and Turkish) and compared their performance on a grammar test with that of 44 native speakers of Dutch. The test consisted of an elicited imitation task and a sentence preference task. In these tasks, participants were tested on their knowledge of dummy subject constructions. These construction types are known to be very hard to acquire for L2-learners of Dutch and are hardly covered in Dutch grammars or L2 Dutch textbooks. The results show that it is possible to attain a native level of proficiency for learners who start acquiring an L2 after puberty, even for learners with a typologically distant L1.