Principals and teachers consider student tardiness to be a serious problem. Some have argued that tardiness is a widespread problem with serious effects, particularly for younger students who must depend on their parents to get them to school on time. Students who are frequently tardy may miss important opening announcements or academic activities. Teachers can become frustrated as late students disrupt instruction, often requiring reteaching of what they have missed. Tardy behavior can also negatively affect the overall classroom environment. Teachers' use of praise is a specific positive reinforcement strategy that has been shown to be effective for addressing problem behaviors in elementary schools. Praise is essentially the use of verbal or written statements acknowledging a desired behavior. Praise has been recognized as perhaps the easiest modification teachers can make to address students' problem behaviors. Teachers' verbal praise can: (1) increase elementary school students' on-task behaviors; (2) decrease their problem behaviors; and (3) improve their academic performance. The appropriate use of praise is also an integral part of the successful implementation of schoolwide positive behavior support (SWPBS). Schools implementing SWPBS focus more on eliminating problem behaviors using positive strategies rather than punishment. However, the use of teacher-written praise to decrease student tardiness within the context of SWPBS has not been examined fully. This article describes a "praise-note" intervention that was designed and implemented in an elementary school to decrease student tardiness within the context of SWPBS. The intervention appeared to improve the students' on-time behavior. Results suggested a functional relationship, with an average of just one praise note per week significantly improving students' tardiness. The article concludes with some suggestions for implementation. (Contains 4 figures.)