|Abstract||After overthrowing Porfirio Diaz in 1910, Mexico's "Revolutionary Family" waged yearly social, economic, political and at times military battles among themselves. Neither the political liberal Madero nor the conservative Carranza could contain the competing workers, peasants, politicos and generals. Obregon and Calles, progressive if not liberal, could. From 1920 to 1928 they attracted the support of most revolutionary elements, including the major political parties, and destroyed the two parties which challenged their rule, In 1928 the assassination of Obregon ended this personalist partnership. During the ensuing succession crisis, Calles established Mexico's first government party. While the Jefe Maximo ruled Mexico through a handpicked president, his supporters managed elections through the PNR. But as Calles grew more conservative his opposition from disgruntled leftists increased. In the resulting struggle both callistas and leftists encouraged the institutionalization of the presidency and the party, the only means to rule for Calles and the only alternatives to conservative personalism for reformers. When Calles chose a reformist president as a concession to the opposition, the new executive used the developing institutions to seize political control of Mexico. To guarantee the permanence of his sweeping reforms, Cardenas incorporated workers and peasants into a reorganized party, the PRM. Although a professed socialist, he did not permit a dictatorship of the proletariat. Instead, he included all major revolutionary elements within his "functional democracy," with the state acting as the final arbiter of their conflicting interests. When his reforms generated opposition from within the broad Revolutionary Family, he responded by expanding the popular sector of the PRM and by choosing a moderate successor for the presidency, Manuel Avila Camacho. The new government emphasized national unity and economic development, primary goals of party moderates that were accepted by many leftists. The PRM's leadership strengthened the popular sector and in 1946 reorganized the party into the development-oriented PRI.