Implied in this descriptive term is the notion that criminal addicts tend to 'specialize' in a pattern of related crime enterprises. Such specialization entails the learning of important skills which not only facilitate the commission of a crime but also facilitate avoiding detection and arrest. The data reveal that while addict criminals do indeed tend to gravitate toward particular types of crime, they do occasionally engage in crimes with which they are not adept. Furthermore, the life history data suggest that addicts are disproportionately arrested for these 'marginal' crimes. While the data are exploratory in nature, the dynamics suggested call into question the validity of official criminal records as indicators of criminal histories among addict populations. (Publisher abstract)