We determined the time and rate of colonization of nonmycorrhizal loblolly pine roots by native ectomycorrhizal fungi during the first growing season following outplanting. The 1974 study conducted on upland and coastal plain pine sites in southwestern Arkansas and southeastern Oklahoma was expanded in 1975 to include additional upland and coastal plain pine sites, and an upland hardwood site. Root tips formed subsequently to outplanting generally became mycorrhizal as they grew into undisturbed soil around the planting hole. Seedlings that had been outplanted in cylindrical plastic tubes developed fewer mycorrhizae and did so much more slowly than did bareroot stock. In both studies there was a steady increase in mycorrhizal development until approximately 16-45 percent of total root tips were mycorrhizal by September-October, 5 months following outplanting. Forest Sci. 23:77-79.