The seasonal abundance and phenology of three Nabis species and their parasitoids were studied in alfalfa (Medicago sativa L.) and soybean (Glycine max (L.) Merrill). Although all three species were present in both crops, differences were noted in composition of the Nabis complex between the two systems. Nabis americoferus (Carayon) was numerically dominant in alfalfa, a crop in which this species produced three generations per year in central Kentucky (USA). In soybean, where one generation is produced, N. roseipennis Reuter rather than N. americoferus or N. rufusculus Reuter produced the greatest number of nymphs for the three consecutive years of study. Sweep sampling recovered fewer in nymphal nabids in comparison with suction or shake sampling and, thus, was less satisfactory in assessing population trends. Parasitoids reared from nabids that had been collected as adults or nymphs in alfalfa or soybean included the tachinid Leucostoma simplex (Fallen) and the braconid Wesmaelia pendula Foerster. Parasitism by the mymarid egg parasitoid Polynema boreum Girault was much higher in alfalfa than in soybean (50% versus 5%).