Previous research documents the positive impacts that teacher praise can have on students' behavior in the classroom; positive praise is a reinforcer that improves and maintains appropriate classroom behavior. Identifying current trends in natural rates of praise--praise that occurs in the absence of specific intervention or training--may help teachers become mindful of their own practices. The purpose of this systematic review was to investigate characteristics of published observational studies of teacher-delivered praise and identify the rate at which teachers delivered praise. We conducted a systematic search of the literature, and included studies published after 2004; 14 studies met our inclusion criteria. The results of this study illustrate that researchers use several different measures to observe and report the frequency of teacher praise. Teachers also delivered general praise (range = 0.04 per min to 67.9 per hour) and behavior-specific praise (range = 5.9-23.14 per hour) at widely variable rates. Teachers commonly used more general praise compared with behavior-specific praise. Across studies, we also found inconsistent rates of teacher praise versus reprimands, with some studies reporting higher rates of praise while other studies reported higher rates of reprimands. We discuss implications for teachers and provide recommendations for future research.