A collection of practical data on organizations involved in astronomy, related space sciences and other related fields. The coverage includes relevant: universities; scientific committees; institutions; associations; societies; agencies; companies; academies; bibliographic services; data centres; dealers; distributors; funding organizations; journals; manufactureres; meteorological services; national norms and standards institutes; parent associations and societies; publishers; and software producers and distributors. After more than 25 years in continuous compilation, verification and updating, the text gathers together over 6200 separate entries from over 100 countries. For each entry, all practical data are listed: city, postal and electronic mail addresses; telephone and fax numbers; URLs for WWW access; foundation years; numbers of members and/or numbers of staff; main activities; publication titles; frequencies, ISS-Numbers and circulations; names and geographical co-ordinates of observing sites; names of planetariums; and awards, prizes or distinctions granted. The entries are listed alphabetically in each country. An index gives a breakdown not only by different designations and acronyms, but also by location and major terms in names. Thematic sub-indices are also provided as well as a list of telephone and telefax national codes.