The Oregon white oak (Quercus garryana) woodland and savanna ecosystems of the Puget Sound lowlands have been dramatically reduced in extent since European settlement due to land use changes and fire suppression. Restoration of these ecosystems often requires planting oak seedlings; however, low growing-season precipitation and excessively drained glacial soils result in droughty conditions detrimental to seedling establishment. The study objective was to determine the effects of irrigation and plastic mulch on volumetric soil water content (VSWC) and first-year growth of planted Oregon white oak seedlings. Three-year-old containerized seedlings were planted on two sites near Olympia, Washington in February, 2004. Soils were Nisqually loamy fine sand and Everett very gravelly sandy loam, both Vitrandic Dystroxerepts. The irrigation treatment was 3.8 liters of water/week/seedling, applied manually from 1 June through 16 July. The mulch treatment was a square, 122-cm-wide sheet of perforated plastic (Brush BlanketŪ; Arbortec Industries, Mission, BC). From late June through July, mulch increased VSWC at 10-30 cm soil depth by three percentage points while irrigation plus mulch increased VSWC by six percentage points. Seedling survival was 100% at both sites. Both irrigation and mulch treatments significantly increased first-year height and diameter growth, but there was an interaction between treatments for height growth. Without mulch, growth of irrigated seedlings (8.8 cm) was similar to that of non-irrigated seedlings (9.5 cm), but with mulch, height growth of irrigated seedlings (29.6 cm) was significantly greater than that of non-irrigated seedlings (14.1 cm). Thus, irrigating at a relatively low rate benefits Oregon white oak seedlings in rapidly draining, glacially derived soils, provided competing vegetation is controlled. In restoration projects where drip irrigation systems are not practical, weekly watering during the early portion of the dry period may be a viable alternative for increasing early growth.