Normative ethics is the study of ethical behaviour and is the branch of philosophical ethics that investigates questions regarding how one ought to act, in a moral sense.

Normative ethics is distinct from metaethics in that normative ethics examines standards for the rightness and wrongness of actions, whereas meta-ethics studies the meaning of moral language and the metaphysics of moral facts. Likewise, normative ethics is distinct from applied ethics in that normative ethics is more concerned with "what ought one be" rather than the ethics of a specific issue (e.g. if, or when, abortion is acceptable). Normative ethics is also distinct from descriptive ethics, as descriptive ethics is an empirical investigation of people's moral beliefs. In this context normative ethics is sometimes called prescriptive (as opposed to descriptive) ethics. However, on certain versions of the view of moral realism, moral facts are both descriptive and prescriptive at the same time.

Most traditional moral theories rest on principles that determine whether an action is right or wrong. Classical theories in this vein include utilitarianism, Kantian ethics, and some forms of contractarianism. These theories mainly offered the use of overarching moral principles to resolve difficult moral decisions.

There are disagreements about what precisely gives an action, rule, or disposition its ethical force. There are three competing views on how moral questions should be answered, along with hybrid positions that combine some elements of each: virtue ethics, deontological ethics, and consequentialism. Virtue ethics focuses on the character of those who are acting. In contrast, both deontological ethics and consequentialism focus on the status of the action, rule, or disposition itself, and come in various forms.

Virtue ethics, advocated by Aristotle with some aspects being supported by Saint Thomas Aquinas, focuses on the inherent character of a person rather than on specific actions. There has been a significant revival of virtue ethics since the 1950s, through the work of such philosophers as G. E. M. Anscombe, Philippa Foot, Alasdair MacIntyre, and Rosalind Hursthouse.

Deontology argues that decisions should be made considering the factors of one's duties and one's rights. Some deontological theories include:

Consequentialism argues that the morality of an action is contingent on the action's outcome or result. Consequentialist theories, varying in what they consider to be valuable (i.e., axiology), include:

It can be unclear what it means to say that a person "ought to do X because it is moral, whether they like it or not." Morality is sometimes presumed to have some kind of special binding force on behaviour, though some philosophers believe that, used this way, the word "ought" seems to wrongly attribute magic powers to morality. For instance, G. E. M. Anscombe worries that "ought" has become "a word of mere mesmeric force."