The coup d'etat of Jiang Jieshi in 1927 brought a sudden end to the first united front between the KMT and the CCP. From then on, the Communist Party was driven underground and survived only with great difficulties, until the second united front was formed in 1937. Yet within the same period, we saw the emergence and growth of concerted left-wing activity in the literary arena. The present thesis is an attempt to look into the background, the development as well as the outcome of this movement, with special reference to the Chinese League of Left-wing Writers, an organization formed in 1930 under the direction and control of the CCP. It covers the period known as "The Left League Decade" in modern Chinese literary history. The thesis is in three parts. Part one discusses the pre-League period, the years before the formation of the League. It deals mainly with the revolutionary literary movement in 1927-28, which in fact consisted of a polemic between the ultra-left, the left and the right over the issue of revolutionary literature. The steps taken for the formation of the united front among the left after this heated debate are analyzed. Part two, which comprises four chapters, is on the League itself. The first is a general survey of the formation, membership and structure of the organization. The second and third chapters discuss the achievements of the League in the first half of its existence. The League then began to decline from 1934 onwards. The internal conflicts which finally led to the alienation of its chief leader and the "giant" of modern Chinese literature, Lu Xun, are presented in great detail in the last chapter of part two. Part three traces and gives an account of the dissolution of the organization and the subsequent Two Slogan Polemic in 1936 over the action to be taken in the new political situation. The relationship between the polemic and the developments in politics takes up a considerable portion of the discussion. Before closing the thesis, an epilogue is attached which looks at the Left League and the left wing literary movement of the thirties in their historical context. It also includes a review of their appraisal in the mainland after the establishment of the People's Republic of China in 1949.