For several decades, the two most controverted questions facing Christians have focused on sex and gender: female ordination and same-sex marriage. Much reflection on both of these questions has been done by Protestant and Roman Catholic, but relatively little by Eastern Orthodox theologians. This book seeks to fill the gap in Eastern Christian reflection by surveying what sources both ancient and modern have to say about human sexual differentiation. After carefully considering the hermeneutical and methodological challenges that arise especially when dealing with patristic texts, the book then seeks answers to the above questions by examining in careful detail the views of three groups of Eastern thinkers: several Fathers from the Greek and Syriac traditions, the Slavophiles in the nineteenth century, and Orthodox theologians of the late twentieth and early twenty-first centuries. In the concluding chapter, a synthesis of these sources is offered and conclusions are drawn for the debates on the ordination of women and marriage of persons of the same sex.