The Dipper (Cinclus mexicanus) is a fairly common breeding bird along streams of the Sierra Nevada. Densities of four pairs per 1.6 km of stream have been recorded in favorable situations (Grinnell and Miller 1944:328). On Sagehen Creek in eastern California, 13 km north of Truckee, Nevada County, I found only one pair of Dippers in 1974 and again in 1975, along 8 km of stream. Recessed rock faces of the sort favored by Dippers for nesting are essentially non-existent along Sagehen Creek, and I concluded that lack of nest sites might be limiting the population. Von Jost’s (1970) report of successful use of nest boxes by European Dippers (C. cinclus) led to the present experiment. Twelve boxes were erected along Sagehen Creek. All were built of ¾ inch plywood following the design (20 cm wide, 18 cm deep, 16 cm high) recommended by von Jost. The boxes were numbered consecutively from the headwaters downstream.