[Apologies if I'm adding something that's already been brought up -- I'm trying to catch up on my list-reading quickly] "Critical Period" effects primarily apply to acquisition of pronunciation; grammar shows much less of an age-related effect. Adult second-languge learners show gaps in mastery of "grammar" typically in areas where one needs a very large amount of exposure to grasp the nuances (e.g. definite article usage) or a very large amount of exposure to encounter a particular item enough times in the first place (e.g. uncommon idioms, colloquialisms). Given enough exposure, adults can demonstrably pass as native speakers *in writing* (Joseph Conrad's writing is distinctive -- but not because it's Polish-y). It's the speech that gives them away. Pronunciation is the part of language most closely tied to motor routines -- "muscle habits" and the like -- and motor routines solidify fairly early on. Non-linguistic motor routines show this kind of effect as well; if you want to be a virtuoso pianist, you'd better start young. And, while there is thus (arguably) a "critical period" for piano virtuosity, claims for such as a specific genetic endowment would seem a bit strained. Bill Spruiell Dept. of English Central Michigan University To join or leave this LISTSERV list, please visit the list's web interface at: http://listserv.muohio.edu/archives/ateg.html and select "Join or leave the list" Visit ATEG's web site at http://ateg.org/