Information technology (IT) professionals have countless opportunities to engage in inappropriate, negligent, and unethical behavior in the development and use of IT. This study explores how different levels of professionalism and Machiavellianism influence the ethical decision making (EDM) involving (IT) issues. Two-hundred and forty graduate students are surveyed using two vignettes depicting ethical IT dilemmas, one of a programmer hacking into bank software and another of an employee using computer equipment for personal work. The results find mixed, but positive support for the ethical decision making model and the effects of professionalism on ethical behavior outcomes. Higher levels of professionalism increased people’s ability to recognize ethical IT dilemmas, use moral equity judgments, engage in ethical behavior, but report unethical behavior less. Machiavellianism decreased the recognition of ethical IT dilemmas and decreased the use of moral equity judgments, but only when the ethical consequences are prominent.