Abstract: Yü yen tzu êrh chi, a progressive course designed to assist students of colloquial Chinese as spoken in the capital and the metropolitan department, is one of the world’s most influential textbooks on Peking Mandarin. It has been officially published three times. This paper first describes the historical context of these textbooks, provides general information of each version, and discusses the current research on the textbooks and the need for further exploration. It then compares and clarifies the volumes, publishing process, printing, binding forms, contents and the names of each of the volumes of the three versions of the textbooks, and raises questions about these versions which require further research, including the “variant versions”, such as transcriptions, sectional copies, truncated versions, reprinted copies, adapted versions, as well as other books modeled on the textbooks’ style.

Key words: Yü yen tzu êrh chi, Thomas Francis Wade, Diplomacy, Peking Mandarin, Version