Nei chia () denotes the "soft style" group of Chinese martial arts, in distinction to the wai chia (Chinese: 外家; pinyin: wàijiā; literally "external school") or "hard style" group, which is associated especially with Shaolin Quan (Shaolin Ch'üan) and its many derivatives. Traditionally, the three arts of T'ai Chi Ch'üan (Taiji quan), Bagua zhang (Pa Kua Chang) and Hsing-i Ch'üan (Xingyi quan) are regarded as internal, although other styles also claim the designation.

The internal/external distinction was apparently described in some martial art related documents dating from the 18th century, and definitively by others in the possession of T'ai Chi's Yang family from at least the second half of the 19th century, and was further categorized in the 1920s by the Chinese philosopher and martial artist Sun Lutang 孫祿堂 (1861-1932), although the principles of the internal school are certainly much older. According to Sun's classification, the principles defining an internal martial art are:

1. Using the mind to coordinate the leverage of the body in relaxation is emphasized in distinction to brute strength.
2. Internally develop, circulate and express qi.
3. External movement principles applied from Taoist tao yin and qigong (also known as nei kung, 內功, nèi gōng).

Some modern theorists believe the descriptions hard and soft were assigned at first, not by the martial artists, but by hypothetical spectators. When they saw a style like T'ai Chi Ch'üan, which looks superficially slow and gentle, by this theory they called it soft. When they saw a style like Shaolin Ch'üan, which has deep horse stances, long punches, and tense, vigorous movements, they called it hard. However, since T'ai Chi was trained secretly until the early 20th century, and in its original forms (as opposed to most modern manifestations of the art) contains many low stances and long punches, most traditionally informed internal practitioners argue the analogy doesn't hold up under scrutiny.

See also

• Chinese martial arts
• Jing (TCM)
• Nei Jin
• Neo-Confucianism
• Taijitu
• Wudangshan
• Zhang Sanfeng