The presentation and interpretation of clinical trial data is of crucial importance to psychotherapy research and practice. This introduction briefly describes how this Special Section on significance testing in clinical trials came about, as well as some of the content included in the articles. Between the original theoretical article and the four invited comments, this Special Section provides a concise and accessible overview of current thinking regarding the limitations of clinical trial data, particularly significance testing, as well as improvements and supplements to these analyses that may benefit both psychotherapy research and those who use this information in applied practice. (PsycINFO Database Record (c) 2011 APA, all rights reserved)