This paper investigates the laws of forbidden marriage as found at the end of the Temple Scroll and in other Qumran texts, and compares them with those of the Sifra and other rabbinic texts. The fundamental problem faced by these sources is the existence of multiple lists of forbidden marriages in the Torah, especially in Leviticus 18 and 20. The two sets of texts take different approaches based on their overall hermeneutical assumptions. The Temple Scroll constructs one harmonized, uniform list, whereas the rabbis use the duplicate commands to derive the prohibitions as well as the liability for punishment for their violation. The differing approaches each essentially reduce the overlapping lists of the Torah to one consistent one, although of course they may vary from each other in some of the details of the specific prohibitions.