Technical Abstract: Use of resistant cultivars is a desirable approach to manage peanut root-knot nematode (Meloidogyne arenaria), and reliable, efficient screening methods are needed. To optimize the resistance screening protocol, a series of greenhouse tests were done using seven genotypes with three levels of resistance to M. arenaria. The three resistance levels could be separated based on gall index as early as 2 weeks after inoculation (WAI) using 8000 eggs/plant, while 4 or more weeks were needed when 1000-6000 eggs/plant were used. High inoculum densities (over 8000 eggs/plant) were needed to separate the three resistance levels based on eggs/g root within 8 WAI. A gall index based on percentage of galled roots could separate the three resistance levels at lower inoculum levels and earlier harvest dates than other assessment methods. The use of eggs vs second-stage juveniles (J2) as inoculum provided similar results; however, it took 3-5 more days to collect J2 than to collect eggs from roots. Plant age affected gall index and nematode reproduction on peanut, especially on the susceptible genotypes AT201 and D098. The genotypes were separated into their correct resistance classes when inoculated 10 to 30 days after planting, but were not separated correctly when inoculated on day 40.