Teacher professional development is to be continuous to ensure its sustainability, indicating the need for unceasing scaffolding provided to the teacher for their professional learning staring with the pre-service teacher education program and going on till their retirement. In-service teacher professional development programs/activities could lead to anticipated outcomes, improved teaching and learning performance, providing they are structured around the real professional development needs of the teacher rather than the ones determined by professional development units of ministries of education or school administration. That is to say, bottom-up professional development activities are more likely to generate desired impacts than top-down ones. In light of this premise, this explanatory sequential mixed methods study aims to identify the professional development needs of in-service English teachers teaching at Anatolian High Schools in the county of Antakya, Turkey. In addition, this study reports on the English teachers' professional development practices. With these purposes in mind, a web survey was distributed to the teachers and the data it yielded were analysed running descriptive statistics. To gain deeper insights into the teachers' professional development practices and needs, a semistructured telephone interview was conducted and the data provided by it was subjected to inductive content analysis. The findings demonstrated that the teachers had been taking a number of steps for their professional development and were mostly in need of taking part in professional development activities that aimed at improving their skills of teaching and assessing speaking. Additionally, the findings pointed to the high value the teachers attached to bottom-up professional development activities.