Higher education literature has always claimed that departmental libraries were less economical than centralized libraries, but faculty traditionally wanted their libraries close to classrooms and laboratories. Still, very little solid evidence is available to support this conventional wisdom. Within this frame of reference, this research was designed to study departmental libraries by collecting and analyzing data on common organizational variables. While previous studies of departmental libraries sought to make administrative comparisons of centralized or decentralized collections, this study examined a set of research questions related to the organizational variables of staffing, educational attainment of the departmental librarian, size of collection, levels of on-line services, budget, users, location, and relations with other units on campus. Data were collected by questionnaire from a sample of American research and doctoral granting institutions, resulting in a stratified sample of 125 of the most commonly occurring types of departmental libraries. The results of the study showed that there were few differences among departmental libraries in these characteristics. There were, however, some important differences among the departmental libraries surveyed concerning the nature and size of their collections and the budgets used to support those collections. Also departmental libraries in the sciences tended to spend a greater proportion of their overall budget for materials than did other types of departmental libraries. Data showed that departmental libraries were staffed by relatively small staffs and headed by a departmental librarian who frequently did not have an additional subject degree or a bachelor's degree in the field of the departmental library. In addition departmental libraries seemed to be most heavily used by students, especially graduate students. Location of the departmental library was most frequently on the main campus within 1/4 mile of the main library.