Self-determination was used after the Treaty of Versailles. This was the belief that newly formed countries and/or ethnic groups decide what government type is best for the country. (class notes)

"V. A free, open-minded, and absolutely impartial adjustment of all colonial claims, based upon a strict observance of the principle that in determining all such questions of sovereignty the interests of the populations concerned must have equal weight with the equitable claims of the government whose title is to be determined." [1]

[1] Wilson, Woodrow. BYU library. N.p., 28 Feb. 2008. Web. 9 Oct. 2009.