Rafael Ángel Calderón Guardia (March 8, 1900 – June 9, 1970) was a Costa Rican medical doctor and politician, who served as President from 1940 to 1944.

After finishing his studies in Belgium, Calderón Guardia became a medical doctor and practicing surgeon, which he would remain for most of his life, even after serving as president.

Calderon Guardia responded to the demand for reform when he assumed the presidency in 1940, and, in doing so, he offered the electorate a viable alternative to the Communist solutions to social questions.

[5] He promised particular attention to the less well developed areas of Costa Rica, such as Guanacaste and the Atlantic region which had been largely abandoned by the United Fruit Company.

[7] He proposed to found a national university that would orient public opinion on social questions and promote the general progress of the republic.

During the war his government imprisoned many Costa Ricans of German descent and confiscated many of their assets including large coffee plantations and banking businesses.

[10] These and other measures were sponsored by Calderon Guardia to build the infrastructure of a socially oriented national economy and to deal, simultaneously and directly, with the pressing needs of the most deprived members of the Costa Rican family.

[11] Calderón developed strong ties with labor organizations, certain important figures of the Catholic Church, such as the progressive Archbishop Víctor Sanabria, and the Communist Party, led by Manuel Mora.

He enjoyed wide support among the poor, but a growing coalition of land owners, industrialists, military leaders, and conservative Church officials strongly opposed him, polarizing society.

Historians Molina and Lehoucq show in Stuffing the Ballot Box: Fraud Electoral Reform, And Democratization in Costa Rica (Cambridge University Press) that leaders of the Republican Party and the PUN agreed to end the civil war and to have Dr. Julio Cesar Ovares rule as interim president for two years and then the TNE would hold new elections; but when this plan was presented to Figueres, he rejected its terms and instead continued to lead his army and win the civil war.

Figueres is celebrated as a national hero in Costa Rica to this day, while Calderón's image remains diminished, in spite of his crucial social reforms.

His daughter Alejandra became a left-wing political activist whose career on a socialist platform was cut short after a deadly road accident in 1979.

Thus, while his social reforms had an enormous impact on Costa Rica, after the congress made the elections of 1948 void and his failed attempts to regain power in 1948 and 1962 hurt his reputation.