In 1966 then-Secretary of Defense Robert McNamara warned the American Society of Newspaper Editors of a "sweeping surge of development" which "has turned traditionally listless areas of the world into seething cauldrons of change." Those "traditionally listless areas," containing over half the global population and two thirds of all nations, are known collectively as the Third World.

Thrust into American consciousness as a result of the seethings and surgings mentioned, the Third World finally has become the object of belated scrutiny by political and historical analysts. Data on 114 nonaligned developing nations has now been collected into a two-volume Encyclopedia of the Third World . Its format is obviously derived from the excellent World Mark Encyclopedia of Nations which has covered this turf for almost two decades. National entries are subdivided into 35 sections ranging from the traditional expositions on geography, language, government, population and economy to discussions of each country's colonial experience, health-care and educational systems, and media. Each entry includes a chronology and bibliography as well.

The justification for an encyclopedia devoted exclusively to the Third World ought ot be the illumination of trends, problems and goals specific tothe developing nations. Unfortunately, this set gives short shrift to such vital issues as unequal distribution of wealth, foreign penetration of industry, agriculture, and the effects of deep indebtedness to multilateral lending institutions on the freedom of governmental action.

Repression, the leitmotif of almost all of the Third World regimes, is measured here on a scale of 1-10 according to the ec-centric human-rights rankings of that long-time outpost of cold warriors: Freedom House in New York. This is particularly surprising considering the availability of accurate, detailed country reports prepared by the Nobel Prize-winning Amnesty International.Statistics which could demonstrate the effects of authoritarian rule are often out-of-date and thus causal connections are blurred. For example, a description of the current repressive military regime in Argentina is followed by labor and health statistics from 1973. Current statistics would document the sharp decline in health-care quality and near-destruction of the organized labor movement since the 1976 military coup.

Yet, despite its failings, the Encyclopedia of the Third World is a useful tool for Americans seeking basic information about these nations. One hopes, however, that it will soon be accompanied on reference shelves by other, more complete source books. (Facts On File, 119 West 57th Street, New York, N.Y. 10019; 2 vols; $70)