Polemonium pectinatum is a species of flowering plant in the phlox family known by the common names Washington Jacob's-ladder and Washington polemonium. It is endemic to the state of Washington in the United States, where it occurs in the Columbia Basin, including the Channeled Scablands and the Palouse. This species occurs in riparian habitat and seasonally moist depressions and bottomlands. Other species in the habitat may include Crataegus douglasii, Amelanchier alnifolia, Elymus cinereus, Rosa woodsii, and Ribes aureum.