Perhaps the most "naturally occurring" data on school misbehavior and aggression are school discipline data, including office referrals, suspensions, and expulsion data. These data constitute the most common markers of school discipline status available on school campuses. There is, however, very little information available in professional or research literature about the reliability and validity of office referrals. This article examines the sources of error that enter into the collection and use of office referrals. Despite these sources of errors, this article documents the importance of considering how office referral data provide information about how discipline systems are functioning on a school campus. Guidelines are provided for utilizing disciplinary data for school safety and school policy planning. (Contains 1 figure, 1 table, and 1 note.)