The paper deals with the role of the Kaitseliit (Defence League) voluntary defence organisation in Estonia’s defence in the years of the Estonian War of Independence (also known as the Liberation War) and in peacetime until 1940, with attention focused mainly on the 1930s. An overview is provided of the historiography, the formation of Kaitseliit in 1918, its role in the Liberation War, the period of decreasing activity of the organisation after the war, and the restoration and development of Kaitseliit in the 1920s and 1930s. The author reviews the objectives of the organisation, issues of its membership, structure, management and armament, as well as the use of Kaitseliit and its units in Estonian military defence and internal training. The paper also attempts to answer the question how the role of Kaitseliit in Estonian national defence developed.