Examination of fibers from a colored fabric fragment from Seip Mound Group, Ohio, demonstrates the utility of sequencing analytical techniques: (1) minimally destructive pretreatment to remove humic acids followed by plasma-chemical oxidation, in preparation for accelerator mass spectrometric determination of radiocarbon age and (2) direct analysis in real time mass spectrometry (DART-MS) of the pretreatment solution, for the determination of red colorants. Pretreatment followed by plasma-chemical oxidation provided the opportunity to date 3 mg of fiber using just 200 mcg of carbon. Examination of the pretreatment solution by DART-MS confirmed the composition of anthraquinones consistent with those from bedstraw root (Galium sp.). The date determined (1,805 ± 35 B.P.) places the textile in the midrange of radiocarbon dates previously obtained for the Seip earthworks; identification of the dye plant shows that the Hopewell possessed a sophisticated knowledge of plants and their uses.