Moral agency is an individual's ability to make moral choices based on some notion of right and wrong and to be held accountable for these actions. A moral agent is "a being who is capable of acting with reference to right and wrong."

Most philosophers suggest only rational beings, who can reason and form self-interested judgments, are capable of being moral agents. Some suggest those with limited rationality (for example, people who are mildly mentally disabled or infants) also have some basic moral capabilities.

Determinists argue all of our actions are the product of antecedent causes, and some believe this is incompatible with free will and thus claim that we have no real control over our actions. Immanuel Kant argued that whether or not our real self, the noumenal self, can choose, we have no choice but to believe that we choose freely when we make a choice. This does not mean that we can control the effects of our actions. Some Indeterminists would argue we have no free will either. If, with respect to human behavior, a so-called 'cause' results in an indeterminate number of possible, so-called 'effects', that does not mean the person had the free-thinking independent will to choose that 'effect'. More likely, it was the indeterminate consequence of his chance genetics, chance experiences and chance circumstances relevant at the time of the 'cause'.

In Kant's philosophy, this calls for an act of faith, the faith free agent is based on something a priori, yet to be known, or immaterial. Otherwise, without free agent's a priori fundamental source, socially essential concepts created from human mind, such as justice, would be undermined (responsibility implies freedom of choice) and, in short, civilization and human values would crumble.

It is useful to compare the idea of moral agency with the legal doctrine of mens rea, which means guilty mind, and states that a person is legally responsible for what he does as long as he should know what he is doing, and his choices are deliberate. Some theorists discard any attempts to evaluate mental states and, instead, adopt the doctrine of strict liability, whereby one is liable under the law without regard to capacity, and that the only thing is to determine the degree of punishment, if any. Moral determinists would most likely adopt a similar point of view.

Psychologist Albert Bandura has observed that moral agents engage in selective moral disengagement in regards to their own inhumane conduct.

Moral agents are entities whose actions are eligible for moral consideration. An example of this would be a young child old enough to understand right from wrong, yet they hit their siblings on an occasion when they get angry. The action of hitting is up for moral consideration because the child is old enough to consider whether or not it is the correct action to take and the morality of their behavior.

Moral patients are entities that themselves are eligible for moral consideration. An example of this would be a child who does not know how to determine right from wrong. A child in this situation is up for moral consideration by others because those around them understand they are incapable of understanding the consequences of their actions and are therefore unable to understand the morality of a situation due to developmental barriers.