The study tested whether violence "spreads" from violent offenders to those inexperienced in violence. Data for the study were originally collected from "Delinquent Networks in Philadelphia: Co-Offending and Gangs." The random sample of offenders was identified through random selection from all official records of arrest (n=60,821) for offenders under age 18 in Philadelphia during 1987. A random number generator was used to pull names of arrested people until 200 offenders who committed a crime alone and 200 offenders who committed a crime with an accomplice had been identified. All crimes committed by offenders between January 1976 to December 1994 were reviewed. The sample for the current study included 235 subjects from the original sample of 400. Members of the accomplice sample included only those 510 co-offenders involved in the target offenders' first co-offense. Crime data for the target offenders and the identifiable accomplices were collected from Philadelphia court records and "rap sheets." The primary independent variable, "co-offending with violent accomplices," was coded for each member of the target sample. Target offenders were considered to be co-offenders with violent accomplices if one or more of their accomplices had previously committed murder, attempted murder, rape, robbery, or aggravated assault or if the most serious charge for the first co-offense was murder, attempted murder, rape, robbery, or aggravated assault. Relying on this criterion, 139 subjects (59 percent) either committed the first co-offense with a violent accomplice or committed a violent crime as a first co-offense; 96 subjects (41 percent) neither committed the first co-offense with a violent accomplice nor committed a violent crime as a first co-offense. Results indicate that nonviolent offenders who commit their first co-offense with violent accomplices are at increased risk for subsequent serious violent crime. Findings suggest that lessons of violence can be learned "on the street," where knowledge is passed along through impromptu social contexts, including those in which offenders commit crimes together. 6 tables, 80 references, and a coding dictionary for crime data