Research has consistently shown there is a negative correlation between age of onset (AO) of acquisition and ultimate attainment (UA) of either pronunciation or grammar in a second language (L2). A few studies have indeed reported nativelike behavior in some postpuberty learners with respect to either phonetics/phonology or morphosyntax, a result that has sometimes been taken as evidence against the critical period hypothesis (CPH). However, in the few studies that have employed a wide range of linguistic tests and tasks, adult learners have not exhibited nativelike L2 proficiency across the board of measures, which, according to some, suggests that the hypothesis still holds. The present study investigated the relationship between AO and UA and the incidence of nativelikeness when measures of phonetic and grammatical intuition are combined. An additional aim was to investigate whether children and adults develop the L2 through fundamentally different brain mechanisms--namely, whether children acquire the language (more) implicitly as an interdependent whole, whereas adults learn it (more) explicitly as independent parts of a whole.