The critical incident technique was used to identify several environmental dimensions relevant to the assessment of a college library, in this case the Cook Library of Towson State College, Maryland. Students were asked to fill out forms describing positive and negative encounters with the library and library staff and to complete a general information form. A detailed schedule was developed to tabulate positive and negative factors in four major areas: staff, materials, services, and physical environment. Results indicated that students were more concerned about the actions and attitudes of the staff and the availability of materials than about the library's physical environment, specific services, organization, or the quality of the collection. (Author/LS)