“…In many areas of linguistic knowledge (and we are not referring here to the morpheme studies of the 1970s), L2 learners also pass through systematic developmental stages that cannot be traced back to properties of their respective L1s or to the target language, such as the use of resumptive pronouns in languages that do not typically allow these pronouns (Tarallo, 1983) or the appearance of overregularization errors with intransitive verbs (Montrul, 2000). Similar developmental errors have been widely documented in L1 acquisition (for resumptive pro-nouns, see Labelle, 1996, andMcDaniel, McKee, &Bernstein, 1998; for causative errors, see Bowerman, 1982). Second, L2 learners have also been shown to acquire very subtle properties of grammar that are not present in their L1, not obvious from the input, or not taught in language classrooms (Bruhn de Garavito, 1997;Dekydtspotter, Sprouse, & Anderson, 1997;Kanno, 1997;Pérez-Leroux & Glass, 1999;White, 2000).…”