Technical Abstract: Tomato spotted wilt, caused by tomato spotted wilt Tospovirus (TSWV), has become a major problem in peanut (Arachis hypogaea L.) producing areas of the southern United States. Development of cultivars with resistance to TSWV appears to be among the most promising methods for managing this disease. As part of efforts toward characterizing breeding lines with potential for release as cultivars, epidemics of spotted wilt were monitored in field plots of runner-type peanut cultivars, Georgia Green and Georgia Runner, and numerous breeding lines from four different breeding programs. Breeding lines were divided into early, medium and late maturity groups. The tests were conducted near Attapulgus, GA and Marianna, FL in 1997 and in Tifton, GA and Marianna, FL in 1998. Early and medium maturing breeding lines, including some genotypes with high oleic acid oil chemistry, were found to have effects on spotted wilt epidemics comparable to those of the moderately resistant cultivar, Georgia Green. No early maturing breeding lines had lower spotted wilt final intensity ratings or higher yields than Georgia Green. However, some late-maturing lines and a smaller number of medium-maturing lines suppressed epidemics of spotted wilt better than Georgia Green, and produced greater pod yields when planted at below recommended seeding rates or thinned to low populations. Several of those breeding lines show good potential for management of spotted wilt. Results from these experiments indicate that there is potential for improving the level of resistance to TSWV in future cultivars. There was no indication that differences in spotted wilt ratings corresponded to differences in numbers of thrips adults or larvae.