The caddisflies of Mount Rainier National Park (MRNP), Washington, USA, were surveyed between 1997 and 2004. At least 1,930 specimens from over 250 collections at 163 sites were examined. Based on the current understanding of caddisfly systematics, 108 species were identified. With nine additional species previously reported that we did not confirm, a total of 117 species are now known from MRNP, representing over 50 % of the reported Washington state caddisfly fauna. The collections of the rare brachycentrid, Eobrachycentrus gelidae Wiggins, represent the second and third known records of adults for this species. Six species, Apatania zonella (Zetterstedt), Asynarchus aldinus (Ross), Limnephilus moestus Banks, Polycentropus flavus (Banks), Rhyacophila vobara Milne, and Neophylax occidentis Banks represent new records for the state of Washington. One new species of Polycentropus was discovered.