Although many changes have swept across the Eastern European communist countries, Bulgaria through the years has remained a bastion of consistency. It is a loyal military ally of the Soviet Union as a member of the Warsaw Treaty Organization (Warsaw Pact), and its economy is inextricably linked to the Soviet Union through bilateral agreements as well as through membership in the Council for Mutual Economic Assistance (COMECON). Of the six Eastern European members of the Warsaw Pact, Bulgaria shares with the German Democratic Republic (East Germany) the distinction of not having contiguous borders with the Soviet Union. It is, however, important geographically because it anchors the southeastern sector of the alliance and borders two member states of the North Atlantic Treaty Organization—Greece and Turkey.

The authors of the Area Handbook for Bulgaria have attempted to describe, comprehensively and objectively, the workings of the economic, political, social, and military systems dominant in the country in the early 1970s as those systems have developed in the post-World War II period. Despite the concentration on the communist era, important historical factors are referred to wherever necessary for understanding the modern scene, and a historical chapter is included to provide the proper setting for the modern state.

The spelling of place names conforms to the transliteration system used by the United States Board on Geographic Names. The use of abbreviations, acronyms, and foreign terms has been held to a minimum. The one abbreviation that necessarily appears throughout the work is BKP for Bulgarian Communist Party (Bulgarska Komunisticheska Partiya). All tons are metric unless otherwise stated. A glossary is appended for convenience, but all unfamiliar terms are explained on first use in the text.