The success of teachers is tied to their effectiveness in managing student behavior. In this meta-analysis, we identified 49 single-case-design studies that evaluated the effectiveness of teacher training on their implementation of behavioral support strategies. Training was most often provided in a one-on-one format (n = 18) and included ongoing coaching (n = 20). Thirty-three of the 49 designs met What Works Clearinghouse standards with or without reservations. The overall between-case standardized mean difference effect size was d = 1.50. We analyzed and grouped teacher- and student-level outcomes as a result of training into five domains: (a) teacher-delivered praise (d = 1.94), (b) teacher desirable behavior (e.g., treatment fidelity; d = 1.22), (c) teacher undesirable behavior (e.g., reprimands; d = 0.87), (d) student desirable behavior (d = 1.88), and (e) student undesirable behavior (d = 1.22). Across all studies, the combined nonoverlap of all pairs scores ranged from 0.37 to 1.0 (M = 0.866). We discuss future areas of research as well as implications for teacher training in behavioral support implementation.