In this dissertation, I describe social, economic and political relations between Jews and Christians in medieval Europe before presenting the intellectual and religious context of Jewish life in Christian Spain. The purpose of this endeavor is to provide the framework for analyzing two works, one in Hebrew and one in Castilian, by the Spanish Jewish author Sem Tob de Carrión (1290- c.1370). Proverbios morales (1355-60), the Castilian text, is important to the Spanish literary canon because it is one of the first works of Semitic sapiential literature to be transmitted, in the vernacular, to a Christian public. However, it has generally been read by scholars of medieval Hispanic literature in isolation from his Hebrew writings. Given that Ma’aseh ha Rav (c. 1345) reveals essential aspects of his thought structure and intellectual milieu not found in Proverbios morales, it should be required reading for a thorough understanding of his worldview. In the Hebrew work, I draw parallels between the polemical language used by Sem Tob and historically documented ideological conflicts that took place among Jews in late medieval Spain and Provençe. Because it is written in a style that involves the weaving together of biblical quotations and allusions, the polemical language must be read in relation to the biblical contexts to which these allusions refer. When analyzed in this way, allegory pertaining to the ongoing dispute among Jews about philosophy and scriptural interpretation, and rebuttals of Christian truth claims, become apparent. Additionally, kabbalistic references and messianic allusions lend the work an esoteric character that sharply distinguishes it from Proverbios morales. This analysis of Ma’aseh ha Rav is used as a basis for comparing rabbinic and philosophical concepts that appear in both works. The general movement from opposition to unity that characterizes each text, and the ubiquitous “golden mean,” link the two works conceptually, and underscore Sem Tob’s preoccupation with harmonizing contradictions on both the spiritual and social levels of existence. This aspect of his thought reflects the general intellectual climate of his milieu, which is characterized by the blending, or intertwining, of the main doctrines of medieval Judaism--philosophy, mysticism, and Talmudic-traditionalism. / text