This experimental study aims to investigate the effects of three vocational English classes, each one academic semester in duration, and using the concentrated language encounter approach and reciprocal peer teaching strategies. This study employed a time-series design with one pre-experiment and two post-experiments. Discourse and frequency analysis were performed in relation to the teachers' English language teaching performance and their students' English listening and speaking performance. The students' reading and writing tests were subjected to analysis of variance with repeated measures, including plotted line graphs. The results revealed a tendency among the teachers and students to increase the frequency of their English language use in each class. The quality of the students' reading and writing were also significantly improved. All teachers expressed positive opinions about the experimental teaching treatment and its effect on the students' English.