Trowbridge’s shrew, Sorex trowbridgii, is distributed from Santa Barbara County, CA, northwards to Washington state, and east along the Sierra Nevada. Five geographic subspecies have been recognized for decades. Until recently, no data were available to describe genetic structure within this species. We will present inferences from mitochondrial cytochrome b sequences, ddRADseq nuclear data, skull morphometrics, pelt coloration, and niche modeling. In general, there is significant genetic structure, possibly at the species level, with some indication of past gene flow or incomplete sorting in some regions. Geographic trends exist in skull shape and size, as well as in coat color.