In February 1927, Jawaharlal Nehru attended the inaugural meeting of the League against Imperialism (LAI) in Brussels. This chapter argues that the Brussels Congress, as it came to be known, was a catalyst in expanding Nehru’s vision for anti-colonial resistance beyond the confines of India or even the British Empire as he came to see the nationalism and anti-imperialist internationalism as mutually interdependent. The LAI introduced Nehru to several critical ideas. The first was that anti-imperialism meant the blending of anti-colonial nationalism and working class mobilization. The second was that imperialism had to be challenged by a global anti-imperialist movement that included leaders in the colonies, advocates for working class equality, and the Soviet Union. Finally, the anti-imperialist movement sought to prevent another world war by overturning the primary causes of war: capitalist and imperialist exploitation of workers and the colonized. Nehru’s political vision came to be informed by these core ideas, and he came to see the Indian anti-colonial movement as interconnected to the global struggle against imperialism.