Abstract
The earliest speculation aimed at understanding the heterogeneity of sexually aggressive behavior took the form of typological systems that attempted to group individuals who had sexually aggressed (ISAs) into distinct types. These speculative systems have over the years been joined by a vast array of studies that have generated hypothetical types using an array of cluster analytic procedures that have used a variety of input measures. Few systematic studies have clearly operationalized these proposed distinctions, reliably assigned individuals to the purported categories, and rigorously tested the validity of the resultant system. Moreover, until recently there were no explorations of whether proposed types represented distinctions in kind versus simply quantitative differences along continua. One program, originally called the Massachusetts Treatment Center (MTC) typology program, has attempted to integrate both deductive and inductive strategies, to generate reliable criteria for classification, to test their validity, and to use taxometrics to explore whether categorical or dimensional models are optimal for studying the heterogeneity among ISAs. This chapter documents the methodological challenges that have plagued the search for ISA typologies and summarizes the progress that this program has made in addressing these methodological stumbling blocks. The important guiding principles that have emerged from this program are discussed, their potential for improving assessment, treatment, and disposition is delineated, and recommendations are proposed about the directions of future research that flow from this program.