Christian Lous Lange was a Norwegian historian, teacher, and political scientist. He was one of the world's foremost exponents of the theory and practice of internationalism.
He was born in Stavanger; his father was a military engineer. He graduated from secondary school in 1887 and proceeded to travel and study history, English, and French at the University of Oslo, from which he received the cand. philol. degree in 1893. He taught at secondary schools for many years and eventually returned to the University of Oslo to receive a doctorate.
In 1899, he had his first official role in the internationalist movement when he was appointed secretary of the committee organizing an Oslo conference of the Inter-Parliamentary Union, an organization dedicated to fostering discussion between parliamentarians of different countries. The next year, he was made secretary of the Nobel Committee of the Norwegian Parliament and, although he gave up the position in 1909, he would play a key role in the early days of the Norwegian Nobel Institute. During this time he was the Norwegian technical delegate to the Second Hague Peace Conference.
Lange rejoined the Inter-Parliamentary Union in 1909 when he was appointed secretary general of the organization, a position he would retain until 1933. As secretary general he oversaw the Union's move to Brussels, sustained it in Oslo through the challenging times of World War I, then moved it again to Geneva after the war. He remained active in numerous other organizations as well, acting as Norway's delegate or alternate delegate to the League of Nations from its founding until 1938, writing reports and acting as a correspondent for the Carnegie Endowment for International Peace, and participating in the Dutch sponsored Central Organisation for Durable Peace, amongst other activities. He was often called upon for his expertise in arbitration and arms control, in particular.