The article begins with a brief outline of the phenomenon of stimulus equivalence and its relationship to human verbal behavior. Relational Frame Theory is then outlined as a behavior-analytic account of both stimulus equivalence and human language. The experimental procedures that have typically been used to examine stimulus equivalence are then considered, before focusing on a series of studies that have developed two alternative procedures for analyzing equivalence class formation: the respondent-type training procedure and the precursor to the relational evaluation procedure. Relational Frame Theory is used to interpret the results that have arisen from these two methodologies. The article concludes that the empirical and theoretical analyses of stimulus equivalence and derived relations, more generally, will be enhanced considerably through the development of a wide range of experimental preparations.