The Kennedy Doctrine was a variant of the earlier Monroe Doctrine in that it defined Latin America as exclusively an American sphere of interest. To that end, the Kennedy Administration endeavored to keep Communism out of Latin America, or at the very least, contain its spread.

The primary effect of the Kennedy Doctrine was to turn Latin America into a major theater of conflict during the Cold War. This was most clearly seen in the Bay of Pigs invasion and the Cuban Missile Crisis. Kennedy and his advisors believed that the Communist Castro regime in Cuba could be removed by force. However, the Bay of Pigs invasion turned out to be a complete fiasco, and its total failure merely served to strengthen the resolve of Cuba to withstand American hostility and aggression. (With the help of the Soviet Union, whose assistance led directly to the Cuban Missile Crisis).

A further effect of the Kennedy Doctrine was that it emboldened all manner of unsavory regimes in Latin America. So long as a particular government was staunchly anti-Communist, it could count on unwavering support from Washington, irrespective of its appalling human rights record. To its credit, the Kennedy Administration did depart from the approach of President Eisenhower by assisting Latin American countries through aid and development. The Alliance for Progress was an attempt to try and alleviate the kind of harsh economic conditions which had often proved a fertile breeding ground for Communism.

However, the more aggressively anti-Communist Kennedy Doctrine undermined the Alliance's goals. The political and social elites of the Latin American regimes supported by Washington were not in the slightest bit interested in implementing serious political and economic reform. They took advantage of the Kennedy Doctrine to enrich themselves and further tighten their grip on power. They knew that when push came to shove, their continued suppression of Communism was much more valuable to the Kennedy Administration than any long-term commitment to domestic change.