The soybean aphid, Aphis glycines, is currently the most important insect pest of soybeans in the Midwest USA. Previous studies have shown a key role of generalist natural enemies as mortality factors for soybean aphid, capable of providing regulation throughout the entire growing season. However, it is unknown what levels of natural enemy suppression are needed to sustain soybean aphid control and under what conditions aphids escape regulation. We conducted a field study using commercial and experimental fields in five locations in Minnesota to quantify the impact of natural enemies on soybean aphid per capita growth rates. In each location, three fields were sampled for aphid and natural enemy populations weekly throughout the field season. In each field natural enemies were sampled using five METHODS: transect counts, plant counts, quadrat counts, sweep nets, and sticky cards. Natural enemy impacts on soybean aphid were recorded weekly by comparing caged plants with open controls for naturally occurring aphid populations. The results of this study will establish: 1) under what combination of abiotic (temperature) and biotic (natural enemies, plant phenology, etc) factors aphids are likely to escape control, 2) what are the key natural enemies influencing soybean aphid field populations, 3) what are the best sampling methods to monitor those natural enemies, and 4) what levels of natural enemy suppression are needed to maintain soybean aphid under control.