The research used a design intended to overcome past criticisms of cross-sectional and panel studies of perceptual deterrence. The 163 participants were all students at Carnegie Mellon University and were mostly middle-aged administrators. Each participant reviewed two scenarios involving the income of a hypothetical plumber. They were asked to estimate the probability that tax noncompliance would be detected and, if detected, the probability that it would result in criminal prosecution. They were also asked to project their own behavior if they were in the plumber's position. The results contrast sharply with prior findings, especially with findings of panel studies. Thus, the perceptions of the risk of detection risk have a strong role in deterring tax noncompliance. In addition, fear of criminal prosecution appears to be a powerful deterrent. Figure, tables, and 35 references.