The present study aims to examine the perceptions of Turkish as a second language (TSL) teachers on in-service training organized to improve their teaching competencies. Therefore, this six-week study was carried out with six teachers working at the Turkish Language Learning Research and Application Centre (TÖMER) of a state university in Turkey. Data were collected via semi-structured interviews. First, the training subjects based on the needs of teachers were determined, and a six-week teacher training programme was established with a group of field experts through distance education. Then, semi-structured interviews were conducted to obtain teachers' perceptions of trainings. In-service teacher training was carried out through online platforms, and interviews were conducted face-to-face. According to the research findings, teachers did not consider distance education and in-service teacher training as effective as face-to-face education, they often hesitated to ask questions. Moreover, teacher training helped the participants increase their awareness and knowledge and identify their knowledge deficiencies. The most effective subjects in teacher training were measurement and evaluation, teaching reading, material development, and grammar, respectively.