Applications on the smartphones that university students frequently use are actively involved in their learning processes. These applications can be used to support students' foreign language development processes in the form of extracurricular activities. The aim of this study is to examine the changes in foreign language development as a result of supporting university students through instant messaging applications. In addition, the views of some of these participants on this process were included in the study. The study was designed as mixed pattern. Quantitative and qualitative methods are used. In the assessments of the quantitative data, paired sample t-test analyzes were performed over the pretest and posttest success scores of 31 participants. Qualitative data were collected through face-to-face interviews with seven participants through a semistructured interview form. Qualitative data were analyzed via content analysis. When the findings of the study are examined, it is understood that instant messaging application is effective. It was determined that the foreign language development of the participants increased significantly in the six-week period. It was also determined that, with the process, the participants started to be more effective in the lessons due to the development of vocational foreign language. In this context, it was stated that the participants' interest in the course increased. It is understood that this situation has positive effects on the self-confidence and motivation levels of the participants. However, it was stated that some participants were bored with the application because they had low interest in foreign languages. Among the suggestions of the study, there is a suggestion that a similar study can be conducted for a longer period of time, and that the participants' foreign language development, changes in the interest and motivation levels of the course can be followed. * Çalışma verileri 2019 yılında toplanmış ve 2020 yılında yayına hazırlanmıştır. Bu nedenle çalışmanın etik kurul onayı yoktur.