This paper investigates the role of amount of current and "cumulative" exposure in bilingual development and ultimate attainment by exploring the extent to which simultaneous bilingual children's knowledge of grammatical gender is affected by current and previous amount of exposure, including in the early years. Elicited production and grammaticality judgement data collected from 136 English-Dutch-speaking bilingual children aged between three and 17 years are used to examine the lexical and grammatical aspects of Dutch gender, viz. definite determiners and adjectival inflection. It is argued that the results are more consistent with a rule-based than a piecemeal approach to acquisition (Blom, Polisenska & Weerman, 2008a; Gathercole & Thomas, 2005, 2009), and that non-target performance on the production task can be explained by the Missing Surface Inflection Hypothesis (Haznedar & Schwartz, 1997; Prevost & White, 2000; Weerman, Duijnmeijer & Orgassa, 2011).