The soybean,Glycine max(L.) Merr., plant introduction ‘PI 227687’ and the susceptible cultivar ‘Davis’ were grown in a greenhouse and evaluated in the laboratory for leaf-feeding resistance to the soybean looper,Pseudoplusia includens(Walker). The effects of an exotic parasitoid,Microplitis demolitorWilkinson, on the development of the looper were also tested. Larvae reared on the plant introduction had longer developmental times, reduced larval weights, and lower consumption of leaves compared with those reared on ‘Davis’. Parasitism byM. demolitorgreatly reduced larval weight and leaf consumption for loopers reared on both cultivars. Although both parasitized and non-parasitized larvae reared on ‘PI 227687’ suffered mortality, the larvae did survive long enough for parasitoid development.