German-born scientist Albert Einstein was best known during his lifetime for his development of the theory of relativity, his contributions to quantum mechanics, and many other notable achievements in modern physics. However, Einstein's political views also garnered much public interest due to his fame and involvement in political, humanitarian, and academic projects around the world. Einstein was a peace activist and a firm advocate of global federalism and world law. He also wrote: “the population of Europe has grown from 113 million to almost 400 million during the last century… a terrible thought, which could almost make one reconciled to war!”. He favoured the principles of socialism, asserting that it was an ideological system that fixed what he perceived as the inherent societal shortcomings of capitalism.

This became especially apparent in his later life, when he detailed his economic views in a 1949 article titled "Why Socialism?" for the independent socialist magazine Monthly Review. He was critical of the methods employed by Vladimir Lenin and the Bolsheviks during the Russian Revolution, stating that they did not have a "well-regulated system of government" and had instead established a "regime of terror" over the fallen Russian Empire. His visible position in society allowed him to speak and write frankly, even provocatively, at a time when many people were being silenced across the European continent due to the swift rise of Nazism in Germany.

In January 1933, Adolf Hitler assumed office as Germany's leader while Einstein was visiting the United States. Einstein, an Ashkenazi Jew, was staunchly opposed to the policies of the Nazi government, and after his family was repeatedly harassed by the Gestapo, he renounced his German citizenship and permanently relocated to the United States, becoming an American citizen in 1940. Though he held a generally positive view of the country's culture and values, he frequently objected to the systematic mistreatment of African Americans and became active in their civil rights movement. As a Labor Zionist, Einstein supported the Palestinian Jews of the Yishuv. However, he did not support the establishment of a Jewish state or an Arab state to replace Mandatory Palestine, instead asserting that he would "much rather see agreement with the Arabs on the basis of living together in peace than the creation of a Jewish state".

Born in Ulm, Einstein was a German citizen from birth. As he grew older, Einstein's pacifism often clashed with the German Empire's militant views at the time. At the age of 17, Einstein renounced his German citizenship and moved to Switzerland to attend college. The loss of Einstein's citizenship allowed him to avoid service in the military, which suited his pacifist views. In response to a Manifesto of the Ninety-Three signed by 93 leading German intellectuals including Max Planck in support of the German war effort, Einstein and three others wrote a counter-manifesto. Einstein accepted a position at the University of Berlin in 1914, returning to Germany where he spent his time during the rest of World War I. Einstein also reacquired his German citizenship. In the years after the war, Einstein was very vocal in his support for Germany. In 1918, Einstein was one of the signatories of the founding proclamation of the German Democratic Party, a liberal party. In 1921, Einstein refused to attend the third Solvay Congress in Belgium, as his German compatriots were excluded. In 1922, Einstein joined a committee sponsored by the League of Nations, but quickly left when the League refused to act on France's occupation of the Ruhr in 1923. As a member of the German League of Human Rights, Einstein worked hard to repair relations between Germany and France.

Einstein moved to the United States in December 1932, where he worked at the California Institute of Technology in Pasadena, California, and lectured at Abraham Flexner's newly founded Institute for Advanced Study in Princeton, New Jersey. Einstein renounced his German citizenship in 1933 due to the rise of Adolf Hitler and the Nazi Party.

During the 1930s and into World War II, Einstein wrote affidavits recommending United States visas for European Jews who were trying to flee persecution and lobbied for looser immigration rules. He raised money for Zionist organizations and was, in part, responsible for the 1933 formation of the International Rescue Committee, a humanitarian organization which gives support and shelter to refugees from social and political persecution.

After World War II ended, and the Nazis were removed from power, Einstein refused to associate with Germany. Einstein refused several honors bestowed upon him by Germany, as he could not forgive the Germans for the Holocaust, where six million of his fellow Jews were murdered. In 1944 Einstein stated "Behind the Nazi party stands the German people, who elected Hitler after he had in his book and in his speeches made his shameful intentions clear beyond the possibility of misunderstanding". Einstein, however, re-visited Germany on a trip to Europe in 1952.

Einstein was a proponent of civil rights and used his renown to condemn American discrimination. When he arrived in America, he objected to the mistreatment of African Americans. Einstein, who had experienced heavy anti-Semitic discrimination in pre-World War II Germany, worked with a number of leading civil rights activists and civil rights organizations (such as the Princeton chapter of the NAACP) to demand equality and denounce racism and segregation.