The Three Principles of the People is a political philosophy developed by Sun Yat-sen as part of a philosophy to improve China made during the Republican Era. The three principles are often translated into and summarized as nationalism, democracy, and the livelihood of the people. This philosophy has been claimed as the cornerstone of the nation's policy as carried by the KMT; the principles also appear in the first line of the national anthem of the Republic of China.

The Three Principles of the People has been reinterpreted by the Chinese Communist Party (CCP) to argue that communism is a necessary conclusion of the Three Principles of the People and thus provides legitimacy for the communist government. This reinterpretation of the Three Principles of the People is commonly referred to as the New Three Principles of the People coined by Mao's 1940 essay On New Democracy, in which he argued that the CCP is a better enforcer of the Three Principles of the People compared to the bourgeois Nationalist Party and that the new three principles are about allying with the communists and the Russians (Soviets), and supporting peasants and the workers. Proponents of the New Three Principles of the People often claim that Sun's book "Three Principles of the People" acknowledges that the principles of welfare is inherently socialistic and communistic.