The transition from elementary to middle school is difficult for many students. However, the association between such transitions and changes in the types and frequencies of student discipline problems has not been adequately investigated. Using data from two school years, infractions and dispositions for all 5th-grade students (N = 4,196) from one school district are followed from the final year of elementary school through the first year of middle school. Results show a substantial increase in reported student discipline problems and the use of in-school suspension in middle school. This increase is most dramatic for subjectively defined infractions like "class disturbance" and "failure to follow rules" compared to more concrete, objective infractions. Implications for educators and school administrators are discussed. (Contains 4 tables.)