This study tests the Competing Systems Hypothesis (CSH) as applied to adult second language acquisition of aspect in Spanish. The CSH purports that differences among tutored and untutored learners result from competition between one system of underlying grammatical knowledge and another of learned metalinguistic knowledge in tutored learners…

The present article provides an exploration of ultimate attainment in second language (L2) and its limitations. It is argued that the question of maturational constraints can best be investigated when the reference population is bilingual and exposed on a regular basis to varieties of their first language (L1) that show cross-linguistic influence.…