THE INSTABILITY OF MOST LATIN AMERICAN COUNTRIES derives to a large extent from the difficulty of incorporating the working class and other popular strata into the political system. Euro ean countries also had to face a similar challenge decades ago, gut the central position they had in the international economic system helped to ease the tensions. In the Third world or Latin America the problem is compounded because to the working class must be added large sectors of urban marginals, peasants and often the impoverished middle classes. These groups tend to form broadly-based parties which become the main contenders for power against the dominant establishment. They are placed in a somewhat similar position to that occupied by Labour, Social Democratic or Eurocommunist parties in Europe or Japan. But they are based on different organizational and ideological elements, and their popular rather than workingclass nature often involves strange coalitions. Brazil and Argentina share fully these traits. In order to understand the characteristics of the popular political parties in those two countries one must examine them in a Latin American comparative perspective.

THE POLITICAL HISTORY OF SOUTH AMERICA COULD ALMOST be written in terms of military coups and returns to barracks. In Argentina, to take only the period since the Second world War, the military has relinquished power in 1946,1958, 1963, 1973 and 1983 (launching coups in 1955,1962,1966 and 1976). The military in Brazil, although less hyperactive than in Argentina, has relinquished power to civilians in 1945, 1955 and, incompletely so far, since 1982, while taking over government in 1954 and 1964. It seems therefore – rather paradoxically for some earlier writers on comparative politics (as was noted in the introduction) – that it is possible to speak of a military-civilian political system operating in much of South America. This features periods of military as well as civilian rule and operates largely because of a high degree of military self-confidence and the willingness of many civilians to contemplate military rule, even over a long period, with equanimity. A mere military coup, or return to barracks, need not imply a change in the political system itself. This point is not tautologous; the politica system may undergo genuine change, but only if civilian attitudes to the military (and willingness to accept military intervention) and military attitudes to civilian politics chan e fundamentally. Is there any sign that this has happened or is about to happen in the cases of Brazil and Argentina?