At the first conference of American Library Association in 1876, Samuel S. Green made a first public statement about reference services in libraries, and pointed out the necessity of providing "personal assistance" to users in selecting and finding materials appropriate to their needs. Approximately one hundred years later, the RASD reference service guidelines appeared. It is the purpose of this article to classified the characteristics of reference services in U. S. during the 80's through discussing the various types of reference services; introducing the RASD (Reference & Adult Services Division) of ALA and its publication, as well as retrospecting the appearance of "A Commitment to Information Services". The author concluded with some suggestions for the development of reference services in the Republic of China.