Despite high staff turnover and a predominance of part-time positions in the field of adult education some adult education teachers create careers for themselves that span many years--even decades. According to the U.S. Department of Education (2007), teachers are the most important factor in improving student achievement. Knapp (2003) points out that professional development is a critical link to improved teaching. Experienced teachers differ from novice teachers in important ways. They are likely to need professional development that affirms the knowledge, experience, and intuitive judgment they have cultivated during their careers. At the same time, teaching experience does not necessarily result in expertise. Some experienced teachers are not as receptive to professional development as are new teachers. Administrators and professional developers must recognize and address this potential resistance while remaining mindful of experienced teachers' characteristics and needs. This brief begins with an overview of the definitions and characteristics of experienced and expert teachers and of the ways that these teachers differ from novice, or beginning, teachers. It continues with a discussion of considerations involved in providing high-quality professional development for experienced teachers. Models of professional development that have been suggested for meeting the unique needs of experienced teachers are presented, and areas for future research are identified. This brief is written for experienced teachers working with adult English language learners and for program administrators and trainers seeking to implement high-quality professional development for these teachers.