This paper describes the rationale, method, automation developments, and future directions of the Air University Library Index to Military Periodicals, a subject index to 81 English language military and aeronautical periodicals. The thesaurus of subject headings, and the software and hardware to produce the Index have all changed over the 40+ years of its existence. Attempts to take advantage of new technology, i.e., a CD-ROM product or a computer file of the Index mounted on an integrated library system, are also discussed.