Vnd is a dual transcriptional regulator that is essential forDrosophila dor-sal–ventral patterning. Yet, our understanding of the biochemical basis for its regulatory activity is limited. Consistent with Vnd’s ability to repress target expression in embryos, endogenously expressed Vnd physically asso-ciates with the co-repressor, Groucho, inDrosophilaKc167 cells.