The Mengzi 孟子 "Master Meng" is a collection of stories of the Confucian philosopher Meng Ke 孟轲 (385-304 or 372-289 BCE, latinized as "Mencius") and his discussions with rulers, disciples and adversaries. It is part of the Confucian canon as one of the Sishu 四书 "Four Books".

Although the history Shiji 史记 states that the author of the Mengzi was Meng Ke himself (together with some of his disciples like Wan Zhang 万章), it must be assumed that at least part of the book was compiled by his disciples after Meng Ke's death. It is seven chapters long, which are each divided in two parts. The titles of most chapters are the names of Meng Ke's conversational partners, like King Hui of Liang, Duke Wen of Teng 滕文公, Gunsun Chou 公孙丑, Wan Zhang, or Gaozi 告子; the chapter Li Lou 离娄 is, in a method also known from the Confucian Analects Lunyu 论语, named after the first words (in this case, the name of a semi-historical person); the same is valid for the last chapter, Jinxin 尽心 "Exhausting all his heart". The arrangement of the chapters is explained by Zhao Qi 赵岐 from the Later Han period 后汉 (25-220 CE) in the following way: Mengzi was of the opinion that the sage rulers of the past, Yao 尧 and Shun 舜, ruled with the methods of humankindness (ren 仁) and proper behaviour (yi 义). These were the most important guidelines for government and had to be explained to a ruler first, in this instance King Hui of Wei (Liang Huiwang 梁惠王). The practical adaption of these principles is explained next (chapter Gongsun Chou 公孙丑), followed by the argument that a revival of the virtues used in antiquity is most important (Teng Wengong 滕文公). In the chapter Li Lou 离娄 the use of the rites (li 礼) is explained that go out of the heart. Of all proper behaviour the most important is filial piety (xiao 孝) that is accordingly described in the next chapter (Wan Zhang 万章). Filial piety arises from affects and character (qing xing 情性), which are explained in the following chapter (Gaozi告子). Man can only control his affects by exhausting all his heart (Jin xin 尽心) to come into one line with Heaven's will. The imperial bibliography Yiwenzhi 艺文志 of the official dynastic history Hanshu 汉书 speaks of eleven chapters, which means that 4 chapters were later added. Indeed, Zhao Qi mentions the titles of four "outer" chapters (waishu 外书: Xingshan bian 性善辩 "Discussing the human nature", Wenshuo 文说 "Explanation from the literature", Xiaojing 孝经 "Classic of filial piety" [not the received Xiaojing!], and Weizheng 为政 "Active government") which are not included in the received version, probably because of their lower quality compared with the seven "inner chapters" (neipian 内篇). Surviving parts of the Outer Book seem to be forgeries by the Ming period scholar Yao Shilin 姚士粦. Zhao Qi, Zhu Xi 朱熹 and Jiao Xun 焦循 were of the opinion that Meng Ke had compiled the book. This assertion is doubted by Han Yu 韩愈, Su Zhe 苏辙 and Chao Gongwu 晁公武 who were sure that the book is a compilation of Mengzi's disciples. Today a middle way between the two competing groups is preferred that also follows the early argument of the historian Sima Qian 司马迁 who said that the core part of the book was written by Meng Ke, while his disciples added some other parts.

For a long time, the book Mengzi was seen as one of the many schools of thought (zhuzi 诸子) and was only classified as a Confucian treatise between the Han and the Tang 唐 (618-907) periods. The Tang period scholar Han Yu, who has written the treatise Yuandao 原道, was the first to said that Mengzi was the real successor of Confucius. It became a Confucian classic only during the Northern Song period 北宋 (960-1126), when it was integrated into the canon of the Jiujing 九经 "Nine Classics". The position of the book was consecrated by the Southern Song period 南宋 (1127-1279) Neo-Confucianphilosopher Zhu Xi, who made it part of the canonical "Four Books". From then on the book Mengzi was part of the canon to be studied to pass the state examinations.

The most important surviving ancient prints of the Mengzi are the small-sized edition version of eight Classics (bajing 八经) from the Song period that was reprinted several times as a facsimile by the imperial household during the Kangxi reign 康熙 (1662-1722), a large-character print from the Song period including Zhao Qi's commentary (reprinted in the collectanea Sibu congkan 四部丛刊 and Sibu beiyao 四部备要, a print of the Nine Classics from 1640 by the Qiugu Studio 求古斋, the edition of the Thirteen Classics with commentaries (Shisanjing zhushu fu kaozheng 十三经注疏附考证) printed by the imperial printing shop of the Hall of Military Glory (Wuyingdian 武英殿) during the Qianlong reign 乾隆 (1736-1795), and the version in theJiaoshi congshu 焦氏丛书, published during early 19th century by the Diaogu Studio 雕菰楼.

The oldest commentators were Zhao Qi (Mengzi zhu 孟子注) and Liu Xi 刘熙 from the Later Han period. Liu Xi's commentary, as well as that of the Liang period 梁 (502-557) scholar Qimu Sui 綦母邃, are lost. Only during the Northern Song period theMengzi attracted the deeper interest of Confucian scholars. There is a commentary traditionally attributed to Sun Shi 孙奭, the Mengzi shu 孟子疏, which is included in the collection Shisanjing zhushu 十三经注疏. The most important commentator of the age of Neo-Confucianism was the Southern Song period scholar Zhu Xi, who has written the commentary Mengzi zhangju jizhu 孟子章句集注, short Mengzi jizhu 孟子集注. The standard Qing commentary is Jiao Xun's Mengzi zhengyi 孟子正义.