Seven substance use pattern categories were created solely on the basis of intensity and duration of self reported drug intake, ranging from little or no use to polysubstance intake on a daily basis. These were applied to data generated from a 19 page structured interview. Results indicated that the heaviest substance users were younger, nonviolent career criminals who acted alone. While they were more likely to have committed the instant offense for drug related reasons, such motivation occurred only 40% of the time. Heavy users were also more likely to have planned some aspect of the offense, others being more spontaneous. (Author abstract)