Data were collected in 3 waves from 1,244 high school students during their sophomore, junior, and senior years from 9 high schools in and around a mid-sized southeastern city. Forty-nine percent were male and 86 percent were white. The two forms of rule-breaking examined were marijuana use and petty theft. The study found that perceived certainty of punishment had a significant and nontrivial deterrent effect on self-reported deviance. In addition, over the 3-year study period, parents' influence diminished and peer influence increased. The perception of clear sanctions influenced the students' behavior only when the effect of moral beliefs weakened. The study concludes that the perception of certain punishment may have a deterrent effect on some forms of common, nonserious delinquency. Panel designs as a methodology of research are not as effective as complete casual models. Appendix. 58 footnotes.