“…Convergence, a different kind of L a !L b interaction, has the outward appearance of monolingual speech; all lexical items occurring in the sentence come from L a , but not all components of the abstract lexical structures belong to L a . Converging speech and mixing, which accompanies attrition or nonbalanced early bilingualism, requires the construction of a composite matrix language (Bolonyai, 1998;Myers-Scotton, 2002;Schmitt, 2000). Although not addressing the question of an actual erosion of L1 competence, Pfaff (1999) documented the course of mixing patterns (Turkish-German) in which the one-time L2, now the preferred language of the preschool bilingual, progressively became the predominant base language in bilingual speech, another example of matrix language ''turnover.''…”