Professional development is considered as an essential element in improving teachers’ competencies which, in turns, enhance students’ learning outcomes. In order to provide useful input for the design of more effective and productive professional training programs, this small-scale study was conducted to investigate EFL high school teachers’ expectations for and experiences of their professional development. Sixty-seven EFL high-school teachers in Soc Trang province in the Mekong Delta were recruited for this descriptive study; they provided information via questionnaire and some of them participated in semi-structured interviews. The study aimed to investigate EFL high-school teachers’ expectations and previous training experiences on seven areas of knowledge for their professional development including (1) teacher’s language proficiency, (2) language teaching methodology, (3) lesson planning, (4) conducting a lesson, (5) assessment of language learning, (6) resources, and (7) technology for language teaching. The findings from this study assist to inform training program developers and administrators in designing appropriate professional training programs and suggest related research areas in the future.