The aim of this study was to analyze, the development of a second language adult learner. Pedro who was the subject of this study is A1 user according to the Common European Framework of Reference, it means that he can make an introduction and use basic greeting and leave-taking expressions. The analysis was based on an interview where the researchers focused their attention on aspects related to phonology, morphosyntax, vocabulary and pragmatics, code-switching, and other anomalies. The results showed that in the participants speaking there are theories, methods, and concepts that are presented implicitly or explicitly. It was also found out that our participant Pedro had many first language interference errors as they were explained along the analysis.