This study is a qualitative case study research, determining the purposes of teachers to use the eTwinning platform and to examine the effects of the platform on teachers. The study group consisted of 15 volunteer teachers who carried out eTwinning projects rewarded with quality labels. In the study, the data were obtained through a semi-structured interview form, and the content analysis method was used in the data analysis. According to the results obtained, it was concluded that teachers used the eTwinning platform in order to make projects, participate in online courses, contribute to their professional development and collaborate. The platform has a great contribution to teachers both personally and professionally. As a result, it is obvious that the eTwinning platform is very useful for teachers. The platform is so effective that it contributes to the professional and personal development of teachers, and even changes their perspective on the profession.