Hirschi has argued that delinquent behavior leads to the development of excuses, which in turn facilitate further delinquency. In this fashion neutralization may serve as a “hardening process” in the development of a delinquent career. This thesis is examined with data from a two-wave panel study of college students' moral evaluations, willingness to accept excuses, and involvement in several minor forms of deviance. A series of analyses and sensitivity checks on the causal model provides weak but fairly consistent support for the hardening process thesis. Several methodological issues in the modeling of change (autoregressive effects, lag periods, interactions) are considered. Greater use of panel models is encouraged, and suggestions for further research on this topic are offered.