This qualitative phenomenological inquiry addressed the research problem of teachers' unfamiliarity with attention-deficit/hyperactivity disorder (ADHD) and its impact on students' educational opportunities. The purpose of this study was to investigate the perceptions of selected middle school teachers in East Texas regarding their training to instruct students diagnosed with ADHD. This study employed phenomenological hermeneutic-interpretive qualitative research, and the study involved 18 teachers from three middle schools in one school district. I used Vygotsky's sociocultural theory to explain how students learn and to suggest strategies and interventions for teachers. This theory focuses on the link between learning and social interaction, addressing both information presentation and behavior issues. The study employed a semistructured interview to gather data, with a particular emphasis on recommended professional development components and experience necessary before teaching students diagnosed with ADHD. I illustrated participants' experiences in the classroom through my presentation and analysis of the challenges and emotions students with ADHD exhibited. Participants explained their responses to students diagnosed with ADHD by drawing on their perception from previous training, knowledge about ADHD, and experience in the classroom. This study extends previous research by highlighting teachers' lack of ADHD training and professional development. By identifying the information needed in teachers' professional development, this research aims to improve teacher training and support for students with ADHD. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]