The purpose of this article is to provide a brief review of the history, development, and current status of the concepts of clinical significance (CS) and the reliable change index (RCI). I address issues regarding the development, criticisms, and applications of CS and RCI. I review the use of normative data, cutoff points, formula adjustments, and the comparative validity of various RCI methods. An examination of the convergence of multiple domains and multiple measures demonstrates ways to further develop the concepts of reliable change and CS. Finally, I make some recommendations and implications for future research and the development of assessment tools.