This article takes into consideration the issue pertaining to the existence of Jewish American identity and its assimilation into mainstream America. It also examines the issues that cropped up after the World War II and the Holocaust belonging to the Diaspora Jewish American society and the conflict b etween the dominant American culture and the Jewish sub -culture. In particular, this study focuses on the condition of the Diaspora Jewish American immigrants, and their changing lifestyle with their assimilation and coming in contact with the Gentiles. To understand the Jewish American society , this article has taken one of the best Jewish American writers, Philip Roth and his works. Philip Roth ’s works chiefly concern with the Jews and their identity and the characters in Philip Roth ’s novels attempt to define themselves either as Jews or not as Jews and this tension creates an ethnic disunity amongst themselves and also within the Jewish society they belong to. The Jewish immigrants after their assimilation and fully adopting the mainland American culture try to deny their Jewish identity and Jewish boundaries by transgressing their own cultural boundaries and limits. This article thus, aims at portraying the conflict between traditional and contemporary morals as manifested in the Diaspora Jewish American immigrants