The Igbo are egalitarian by nature. They are known to be a people who believe in the mutual complement of everybody’s efforts and mutual unity among all parts that form the whole. However, the dehumanizing Osu caste system has divided the Igbo and alienated some segment of the Igbo society. The main aim of this study is to find out the effects of the Osu caste system on socio-political development in Imo state. This study uses primary and secondary sources of data collection using interview as main research instrument to reduce bias in providing information for analysis. The theory that guided this study is the theory of legitimation which assumed that the actions of an entity or society are deemed desirable, proper or appropriate within some socially constructed system of norms, values, beliefs and definitions. The major finding is that the Osu caste system affects political development in Imo State. The researcher therefore recommends that the Osu caste system should be abolished because it is inimical to both human and societal development.