The purpose of this thesis is to analyze the Communist League through Marxist party theory. This thesis used the official documents of the Communist League, Marx''s own writings on the Communist League and the Revolution in 1848 as the research datum. Firstly, this study reviewed Marxist party theory from the standpoint of five topics such as the need for the political struggle and political party, vanguard party and mass party, the role of party, the democracy in the party, the bureaucratized party.
Marx formulated the principle of self-emancipation of the working class, and emphasized the need for the socialist party and the combination of economic struggle and political struggle. Lenin established the principle of the construction of socialist party to combine the working class with the socialist. Rosa Luxemburg criticized the centralized elitist party and emphasized the voluntary struggle of the masses. Gramsci insisted on the change in civil society embraced by the capitalism as well as the overthrow of the capitalist state power. Gramsci paid attention to the role of the intellectuals and the party that can organize the resistance to the capitalist superstructure and ideology. Trotsky separated Stalinist party from Leninist party, and criticized the bureaucratized Stalinist party. This criticism passed down to the European effort to restore the tradition of Leninist party after the collapse of Stalinist regime.
Marxist party theory has been changed to meet the practical needs depending on the various situations. We also need to establish our party theory to meet the practical needs depending on our own situations. In establishing our party theory we should consider the development of capitalism and the working class, the oppression of ruling class, the relationship between the working class and the other classes.
This study analyzed the issues of Marxist party theory practically through the example of the Communist League. This study illuminated Marx''s will to build a democratic socialist party by investigating Marx''s efforts to transform the Communist League from the conspiracy organization to a popular revolutionary organization. According to Marx, the socialist party is the independent workers party and had better be reunified in one party if it is possible. The socialist party excludes the farmers and the petty-bourgeois from its organization, but should continue to cooperate with them to win the revolution. The socialist party basically has to develop popular propaganda and mass struggle, and utilize parliament and election to meet the given conditions.
In conclusion, Marx''s socialist party through the Communist League is the democratic socialist party with popular propaganda and mass struggle in the workers mass organization in case a legitimate socialist party is impossible.

Key words: Marx, Communist League, party, revolution, socialist, Lenin, Luxemburg, Gramsci, 1848.