Self-monitoring is a popular, efficient, and effective intervention that is associated with improved academic and social behavior for students across age and ability levels. To date, this is the first study to directly compare the outcomes of self-monitoring functionally relevant and non-relevant replacement behaviors. Specifically, we used an experimental single-subject reversal design, with counterbalanced condition order, to document the relationship between types of self-monitoring (functionally relevant vs. nonrelevant) and off-task behavior for 2 at-risk middle school students. Across both participants, levels of off-task behavior were lower when a functionally relevant intervention was implemented than when a functionally nonrelevant intervention was implemented. Implications and limitations are discussed. (Contains 1 table and 2 figures.)