The present study analyzed the effect of social interaction and corrective feedback on developing oral and written communication skills in ESL students. The sample was made up of 120 intermediate-level participants in a language institute. A quasi-experimental design with a control group was used. Participants were assigned to groups with high vs. low social interaction and different types of feedback. Oral and written expression was measured before and after using standardized tests. The quantitative analysis showed positive correlations between social interaction and oral (r = 0.42) and written (r = 0.30) performance. Focused feedback had greater effects on grammatical accuracy than indirect feedback. Qualitative analysis through interviews revealed mostly positive perceptions about the value of interaction and feedback. Triangulating quantitative and qualitative results allowed a deeper understanding of the topic. In conclusion, both meaningful social interaction and corrective feedback facilitate the acquisition of communicative skills in English as a foreign language. These findings have implications for promoting a communicative and interactive approach to English teaching, emphasizing collaborative tasks and effective feedback. It is recommended that this line of research be continued by replicating the study in other contexts and performance levels.