This study aimed to investigate the professional development needs of Turkish as a foreign language teachers and to examine whether there was a difference among the professional development needs of teachers with different educational backgrounds. To this end, the professional development needs of teachers were first investigated through a questionnaire administered to a total of 160 participants. Then, 15 teachers were interviewed in focus groups randomly selected from Turkish teaching centers (TÖMER) in Ankara. The population of the study was teachers working in Turkish language centers and institutes around Turkey. As a research method, the explanatory sequential mixed method was used. In the analysis of the data, descriptive and prescriptive statistical analyses were conducted and content analysis was used in the analysis of the interviews. Findings revealed that teachers needed to develop speaking and writing skills in both assessment and teaching. Professional development needs of the teachers varied according to age, occupational experience, the department they graduated from and the latest graduation degree. Finally, pedagogical implications of our research are briefly considered.