One exception to this pattern was nonindex status offenses committed during adolescence. These offenses tended to be planned for the purpose of 'having a good time,' 'getting excitement,' or 'relieving boredom.' Offenders who committed crimes impulsively tended to exhibit greater involvement in crime than those who planned their crimes. Their impulsive criminality was apparently the expression of a general lifestyle of violence and impulsivity ungoverned by normative social values. Their crimes tended to be more harmful than crimes that were planned. In an effort to counter the crimes committed by impulsive offenders, sentencing should focus on the harmful consequences of an offense rather than the degree of planning involved, and social control efforts should emphasize the reduction of opportunities for typical impulsive crimes. The high proportion of all types of crime committed impulsively suggests the importance of the microanalysis of offense situations. 7 tables. (Author summary modified)