On May 17, 1936, Colonel David Toro Ruilova (1936-37) overthrew Tejada in a military coup. Because the officer corps wanted to avoid a civilian investigation of the military's wartime leadership, military backing for the coup came from all ranks. The main backers, however, were a group of younger officers who wanted to bring profound change to Bolivia. Toro, the leader of this group, hoped to reform the country from the top down. His program of "military socialism" included social and economic justice and government control over natural resources. He also planned to set up a corporate-style political system to replace the democratic system established in 1825.

Toro attempted to get civilian support with far-reaching social legislation and nominated a print worker as the first labor secretary in Bolivia. He also nationalized the holdings of Standard Oil without compensation and called for the convening of a constitutional congress that would include the traditional parties, as well as new reformist groups and the labor movement.

Toro was unable, however, to enlist lasting popular support. A group of more radical officers resented his reluctance to challenge the rosca, and they supported a coup by Colonel Germán Busch Becerra (1937-39) in 1937. A new constitution, promulgated in 1938, stressed the primacy of the common good over private property and favored government intervention in social and economic relations. It also legally recognized the Indian communities and included a labor code. In 1939 Busch challenged the interests of the mine owners for the first time by issuing a decree that would prevent the mining companies from removing capital from the country. None of his policies, however, resulted in significant popular and military support, and they completely alienated the conservative forces. Frustrated by his inability to bring about change, Busch committed suicide in 1939.

Despite the weakness of the Toro and Busch regimes, their policies had a profound impact on Bolivia. Reformist decrees raised expectations among the middle class, but when they failed to be implemented, they contributed to the growth of the left. The constitutional convention gave the new forces for the first time a nationwide platform and the possibility of forming alliances. The military socialist regimes also prompted the conservatives to join forces to stem the growth of the left.

Data as of December 1989