Huddersfield University Library (England) has undertaken a wide range of evaluative studies of its services and systems, using various data collection techniques such as: user surveys; exit interviews; online and CD-ROM analysis; benchmarking; user groups; staffing and staff development evaluation; suggestion sheets; student project work; group review; services statistics; and focus groups. Focus groups involve people--users or customers possessing similar characteristics such as environment, knowledge, and background--who participate in focused discussions on a specific topic, and thereby provide qualitative data. Unlike the other evaluation methods, focus groups are used to: (1) gain relatively fast reaction to subjects perceived as needing improvement or change; (2) improve communication or an understanding gap between groups such as students and staff or staff and library staff; (3) generate ideas; and (4) provide additional information to combine with other measurement methods. The procedures used at Huddersfield for organizing focus groups and some experiences are discussed. Focus groups provide new and unexpected insights into user perceptions, behavior, and attitudes which are vital if libraries are to successfully manage their resources and environment. When used in the context of other performance evaluation and measurement methods, focus groups can provide a much more detailed insight into how libraries are perceived and used. (SWC)