Moral development focuses on the emergence, change, and understanding of morality from infancy through adulthood. The theory states that morality develops across the lifespan in a variety of ways. Morality is influenced by an individual's experiences, behavior, and when they are faced with moral issues through different periods of physical and cognitive development. Morality concerns an individual's reforming sense of what is right and wrong; it is for this reason that young children have different moral judgment and character than that of a grown adult. Morality in itself is often a synonym for "rightness" or "goodness." It also refers to a specific code of conduct that is derived from one's culture, religion, or personal philosophy that guides one's actions, behaviors, and thoughts.

Some of the earliest known moral development theories came from philosophers like Confucius, Aristotle and Rousseau, who took a more humanist perspective and focused on the development of a sense of conscience and virtue. In the modern-day, empirical research has explored morality through a moral psychology lens by theorists like Sigmund Freud and its relation to cognitive development by theorists like Jean Piaget, Lawrence Kohlberg, B. F. Skinner, Carol Gilligan, and Judith Smetana.

Moral development often emphasizes these four fundamentals:

Morality refers to “the ability to distinguish right from wrong, to act on this distinction and to experience pride when we do the right things and guilt or shame when we do not.” Both Piaget and Kohlberg made significant contributions to this area of study. Experts in developmental psychology have categorized morality into three key facets: the emotional aspect, the cognitive aspect, and the action-oriented aspect.

Moral affect is “emotion related to matters of right and wrong”. Such emotion includes shame, guilt, embarrassment, and pride; shame is correlated with the disapproval by one's peers, guilt is correlated with the disapproval of oneself, embarrassment is feeling disgraced while in the public eye, and pride is a feeling generally brought about by a positive opinion of oneself when admired by one's peers.

Empathy is also tied in with moral affect and is an emotional unfolding that allows you to be able to understand how another person feels. If an empathetic person sees someone crying, then they may understand their sadness. If the empathetic person sees someone that has just accomplished a lifelong goal, they may understand their happiness. Empathy falls under the affective component of morality and is the main reasoning behind selflessness. According to theorist Martin Hoffman, empathy plays a key role in the progression of morality. Empathy causes people to be more prominent in prosocial behavior as discussed earlier. Without empathy, there would be no humanity.

Moral reasoning is the thinking process involved in deciding whether an act is right or wrong. This allows the development of social cognition, which is required for experiencing other people's distress. These skills also enable the construction of a concept of reciprocity and fairness, allowing people to go beyond mere egocentrism. According to Piaget and Kohlberg, moral reasoning progresses through a constant sequence, a fixed and universal order of stages, each of which contains a consistent way of thinking about moral issues that are all distinct from one another.

Based on the observing of others and modelling behaviours, emotions and attitudes of others. This theory is derived from the concept of perspective behaviourism but has elements of cognitive learning as well. The theory says that people especially children learn from observing others and the environment around them. It also says that imitation modelling has a major role in the learning and development of the person and their beliefs or morals. Albert Bandura was a major contributor to the theory of social learning and made many contributions to the field with social experiments and research. The social learning theory says that children learn and develop morals from observing what is around them and having role models that they imitate the behaviour and learn. Role models guide children in indirectly developing morals and morality. By watching the responses of others and society around them, children learn what is acceptable and what is not acceptable and try to act similarly to what is deemed acceptable by the society around them.