Fajia (Chinese: 法家; pinyin: fǎjiā), or the School of fa (laws, methods), early translated as legalism for Shang Yang, is a school of thought representing a broader collection of mainly Warring States period classical Chinese philosophy, incorporating more administrative works traditionally said to be rooted in Huang-Lao Daoism. Addressing practical governance challenges during a time when traditional feudal systems were collapsing, their ideas 'contributed greatly to the formation of the Chinese empire' and bureaucracy, advocating concepts including rule by law, sophisticated administrative technique, and ideas of state power. They are often interpreted in the West along realist lines. The Qin to Tang were more characterized by their traditions.

The school incorporates the more legalistic Li Kui and Shang Yang, and more administrative Shen Buhai and Shen Dao, with Shen Buhai, Shen Dao, and Han Fei traditionally said to be rooted in Huang-Lao (Daoism), as attested by Sima Qian. Shen Dao may have been a significant early influence for Daoism and administration. These earlier currents were synthesized in the Han Feizi, including some of the earliest commentaries on the Daoist text Daodejing. The later Han dynasty took Guan Zhong to be a forefather of the school, with the Guanzi added later. Later dynasties regarded Xun Kuang as a teacher of Han Fei and Qin Chancellor Li Si, as attested by Sima Qian.

With a lasting influence on Chinese law, Shang Yang's reforms transformed Qin from a peripheral power into a strongly centralized, militarily powerful kingdom, ultimately unifying China in 221 BCE. While Chinese administration cannot be traced to a single source, Shen Buhai's ideas significantly contributed to the meritocratic system later adopted by the Han dynasty. Sun Tzu's Art of War recommends Han Fei's concepts of power, technique, wu wei inaction, and impartiality, punishment and reward. With an impact beyond the Qin dynasty, despite a harsh reception in later times, succeeding emperors and reformers often recalled the templates set by Han Fei, Shen Buhai and Shang Yang, resurfacing as features of Chinese governance even as later dynasties officially embraced Confucianism.