Excerpts from the Preface: This circular contains references to more than 400 studies pertaining to selected aspects of the extension educational function. For the most part, studies mentioned bear publication dates covered by the period 1954 through 1958, or became known to the Federal office during that period. They are arrayed alphabetically by authors according to the major areas and subareas of the outline that serves as the contents page. Included for each study are appropriate bibliographic notations and brief comments on study base and methodology. Included as a separate section is an alphabetical author listing accompanied by numbers to identify the studies with which each is associated.