Why do state legislators enact policies that conflict with their immediate self-interest? I address this question by assessing the impact of traditional and non-traditional policy determinants on ethics policy adoption. Specifically, I use event history analysis to identify the factors that explain the authorization of independent state legislative ethics commissions from 1973 to 1996. I find that the determinants of ethics policy are substantially, but not completely, different from those of other policies, with ethics policy fitting into an agenda-setting model better than many other policies. Scandals and the actions of other states played a prominent role in setting the agenda and facilitating the authorization of ethics commissions. The agenda-setting process transforms the immediate self-interest of legislators on this issue from one of concern about their own economic well being to one of concern about re-election. In addition, political culture, institutional power arrangements, legislative compensation, and party competition had small but discernible effects on the likelihood of a state establishing a legislative ethics commission.