The study found that changes in local life circumstances (LLCs) significantly affected offending patterns; for example, offenders were relatively more specialized in their offending at times when they were married than when they were unmarried. Marriage may thus constrain opportunities for a diverse array of crimes. Findings also suggest that changes in LLCs toward higher levels of drug and alcohol use are likely to result in increased crime diversity. This may reflect exposure to broader groups of deviant peers. It is also possible that the substance use itself impacts offending behavior by altering individuals' perceptions of sanctions risks. Further, the study found that LLCs are not only related to the types of criminal acts committed in the short term but also the overall frequency of offending. The findings suggest that the dynamics of offending specialization/diversity require consideration of both the nature of situational contexts that pertain to crime opportunities and the strength of the individual's current motivation to commit crimes. Study data were based on a sample of 658 convicted male offenders incarcerated in Nebraska during 1989 to 1990. Study participants completed surveys during an interview that obtained information on LLCs in the months leading up to the arrest that resulted in their conviction and incarceration. The focus was on the calendar year of the arrests as well as the two calendar years prior to the arrest year. The measurement period ranged from 25 to 36 months. The dependent variable was the diversity index related to crime types. The independent variables pertained to LLCs and offending frequency. Control variables included age of crime onset, current age, and race. 2 tables, 15 notes, and 97 references