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Blue (Quercus douglasii Hook. & Am.) and valley (Quercus lobata Née) oak seedlings were planted on a foothill rangeland site in 1987 and 1988. Both species were watered their first year but received no irrigation thereafter. They were evalu­ated during each subsequent spring and summer for survival, weekly height growth and total year-end height. Seedling sur­vival was extremely high for both species and height growth was rapid and vigorous. Blue oak seedlings four growing seasons after planting averaged over 2.3 m and valley oaks after three seasons averaged 2.0 m in height. Yearly height growth occurred in a series of flushes beginning around the end of March. Typical seedlings had either two or three flushes, although the average number per year has been declining. During flush periods, growth was rapid, often exceeding 15 cm per week. The greatest height increment occurred during the second flush. These results suggest that both blue and valley oaks have the capacity to grow rapidly as young seedlings if suitable environmental conditions are maintained. (source abstract).