In contemporary normative ethics, deontology is a theory according to which agents deliberate about how they ought to act and evaluate whether their actions are right or wrong. On a rough characterization, deontology prioritizes the right over the good. Therefore, deontological normative theories require, forbid, or permit actions as a matter of principles, largely regardless of the outcomes produced by those actions. In contemporary normative ethics, the foil for deontology is consequentialism, with the latter prescribing and evaluating the rightness or wrongness of an action solely according to the consequences brought about by that action. This entry identifies some of the characteristics of deontological moral reasoning, including its contractualist variety. To better appreciate these characteristics, the entry works through some thought experiments, aiming to highlight the distinctions between deontology and consequentialism.