Chos?n Korea ushered in a period of rapid development in Confucianism. The government of Chos?n began an anti-Buddhist policy based on to the social and cultural changes affected by Confucianism. Most notably, Buddhist monks were ousted from political power, Buddhist property was confiscated, and the construction and holding of land outside highly populated areas, such as the capital, were highly regulated.

Chinese Confucian rites, called 'ye,' reached into almost every part of Chos?n's aristocratic elite. The lifestyle and behavior of Chos?n's elite were prescribed in painfully minute detail, and included all facets of life: court procedures, ceremonies, customs, language, music, and all principles governing human interaction.

The School of I, also known as S?ngnihak (moral and natural law) became the dominant branch of Confucianism during the Chos?n dynasty. This was essentially a theory of spiritual monism and that an all pervasive force was behind the universe called the Supreme Ultimate (T'aeg?k) which is further divided into two relative opposites, the yin and yang.

Neo-Confucianism was primarily concerned with the regulation and harmonization of human relations through moral and ethical principles, as opposed to orthodox Confucianism which sometimes delved into metaphysical problems, such as the origin and nature of the universe, yet left the average scholar hanging when it came to practical explanations on how to live a good life.

A major book in Neo-Confucian thought is the Book of Self-Cultivation (Susins?) published in Chinese in 1431, and Korean in 1481. It emphasizes Confucian virtues such as: self-control, loyalty, self-cultivation, and filial piety. Neo-Confucian ethics dealt with three cardinal principles, called samgang: 1) loyalty to ruler, 2) filial piety to parents, and 3) faithfulness, chastity, and fidelity. There were also five ethical norms, called oryun, which dealt with human relationships, such as: 1) righteousness and justice between rulers and ministers, 2) cordiality and closeness between parents and children, 3) distinction between husband and wife, 4) order between elders and juniors, and 5) trust between friends.