This study aimed to explore the perceptions and experiences of tertiary level Turkish ELF teachers regarding self-initiated professional development, and to find out if their perceptions differed according to their demographics. For this mixed-methods study, the quantitative data was collected from 67 Turkish EFL teachers through surveys, and one-on-one interviews were conducted with 14 of them. Descriptive and inferential statistics were used to analyze the quantitative data, and for the analysis of the qualitative data, content analysis was used. The results showed that teachers valued collaboration greatly and thought professional development should be context-specific, address their needs, provide practical information and help them be up-to-date. They also asserted teachers should have more autonomy about their own professional development and receive financial, attitudinal, and time-related support from their institutions. The results also indicated that teachers having an undergraduate or graduate degree in teaching English as a foreign language put greater emphasis on the duration of professional development compared to the teachers who graduated from a non-TEFL program, did not have a master’s degree or had a master’s degree in a non-TEFL program. Moreover, sharing experiences and problems with colleagues was the most experienced professional development activity by the participants, whereas attending article discussion club sessions was the least experienced one. Moreover, teachers found attending certificate/diploma programs to gain teaching qualifications the most beneficial, but preparing portfolios was found to be the least useful professional development activity for them.