It is the contention of this paper that libraries are accountable and that library performance can be measured under the accountability concept. Accountability includes three aspects: (1) basic principles, (2) performance objectives and (3) educational engineering. In order to explore this position, the following topics are dealt with in this paper: (1) What are the basic principles of educational accountability? (2) How do these principles apply to library accountability? (3) What are performance objectives in the educational context? (4) How do performance objectives apply to library programs? (5) How does Lessinger's concept of educational engineering relate to library management? (6) Example of the use of a specific library performance objective and (7) Conclusion. Library accountability is a challenge which must be faced if libraries are to continue to receive public support. With effective planning and management, it is now possible to measure some aspects of library performance in terms of direct benefit as perceived by the individual user. (Author/NH)