Despite the fact that deterrence theory has been widely studied in the criminological literature, there is an incomplete understanding of the deterrence process because almost all of the research has focused on how the knowledge of official sanctions and other information affect a would-be offender’s decision about whether or not to offend. By concentrating so fully on this question, researchers have failed to examine how knowledge of official sanctions and other information influence a would-be offender’s perceptions about the risks involved with criminal behavior. Previous research has suggested that deterrence is a continual process that unfolds over time; the current article develops a framework through which perceptions of sanctions are modified in response to involvement in criminal activity and the consequences of the criminal activity. The model was tested using 2 waves of data from 1,530 10th grade students enrolled in 9 schools across the southeastern United States. Participants completed self-report questionnaires measuring estimates of punishment certainty for various crimes, past and current offending behavior, number of arrests, and peer offending behavior. Results of regression analyses indicate that the way in which new information concerning sanctions influences perceived certainty of punishment is largely determined by the level of perceived punishment certainty prior to the new information. One of the most significant determinants of change in perceived sanction certainty over time was the extent of peer offending, followed by arrest. Individuals who have peers who frequently offend are less likely to perceive the certainty of sanctions. Thus, vicarious experiences have a significant impact on perceptions of sanction threat. Future research should focus on how different types of sanctions influence and alter perceived sanction threats. Tables, appendix, references