Investigating the Impact of Interlanguage on Adult EFL Learners in Indonesia: Strengths and Weaknesses

The study of second language acquisition (SLA) concerns not only the way to learn a (L2), but also unique system created by learners (interlanguage). This qualitative analyzed EFL learners’ interlanguage focusing on their strengths and weaknesses in speaking English, especially phonological, grammatical pragmatic competence English. data were obtained from recorded conversation between two non-native English speakers Indonesia. analysed referring contrastive analysis, error analysis socio-cultural perspective SLA. results indicated that although both had strong L1 accent, did face any difficulty constructing sentences right sentence order (SVO). In addition, when facing difficulties seen ask provide support each other, as well talk themselves (private speech). terms weaknesses, found often mispronounced letter “t” sound Indonesian, made errors subject verb agreement, applied Indonesia’s concepts suggests it is necessary have positive view can be used tool language.
 Keywords: Contrastive interlanguage, acquisition,