The purpose of this study is to update the research regarding perceptions of specific challenging behaviors that teachers find to be most prevalent and/or problematic. This study analyzes the role of teacher demographics (gender, race, grade level, and years of experience) on their perceptions of specifically defined challenging behaviors. After conducting a comprehensive review of the literature, nine categories of challenging behaviors in schools and classrooms were created. Using these definitions, this study analyzed 800 surveys of kindergarten through twelfth grade teachers in five districts of one state to measure their perceptions of these nine categories of challenging behavior. Teachers were also surveyed for demographic data to investigate response patterns for different challenging behaviors. Analyses indicated that "Off-task" was the most prevalent and problematic challenging behavior and "Isolation/No social interaction" was the least prevalent and problematic challenging behavior. Statistically significant differences in ratings were noted according to gender, grade level and years teaching. Limitations and future directions are discussed.