The widespread adoption of the Computers and Information Technology in every field has opened up immense possibilities for using Information Technology in an unethical manner. Cases of hacking, software piracy etc. have become major concerns. However the IS literature is somewhat limited on this. Specifically, the factors leading to such behavior have not been generically studied in detail. The paper aims to fill this gap and tries to develop a model of unethical IT usage based on the underlying framework of the Theory of Reasoned Action (TRA). Drawing from research in IS, psychology, ethics and a little of Transaction Cost Economics, it adapts the TRA to the IS context and posits individual, social and technological factors as important in understanding unethical IT usage. This paper, currently research in progress, develops the model and includes propositions that can be developed into testable hypotheses for empirical work.