Graduate students in school psychology, school counseling, and school social work are training to work as school-based professionals. In their professional roles, they work with students facing a variety of academic, social, and psychological challenges, including students who are developing their understanding of their own sexual orientation, gender identity, and gender expression. Students whose sexual orientation, gender identity, and gender expression fall outside of what is considered "normal" face significant personal harassment and institutional discrimination (Kosciw et al., 2014; Rankin et al, 2010; Silverschanz et al., 2008; Waldo, 1998; Woodford et al., 2014; Woodford & Kulick, 2014). To date, no research has examined the experiences of harassment among LGBT graduate students training to work as school-based professionals. Building off of extant literature that has examined the experiences of college and graduate students broadly, this study sought to examine whether graduate students in school psychology, school counseling, and school social work face heterosexist harassment that impacts their psychological functioning, academic wellbeing, and attitudes toward sexual minority individuals. Graduate students (N = 297) in school psychology, school counseling and school social work completed an online survey examining heterosexist harassment, psychological functioning, academic wellbeing, and attitudes toward sexual minority individuals. The results of the study found sexual minority are the most likely to experience heterosexist harassment, but that heterosexual students are not immune from this harassment. Additionally, the current study found that individuals who experienced heterosexist harassment had decreased psychological functioning and less favorable perceptions of the climate of their training program. No differences were found in the frequency of harassment experienced and attitudes toward sexual minority individuals. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]