Widespread infestation of soybeans with soybean aphid across Wisconsin continues to be a major problem for soybean producers in the state. In 2001 we began a research project to examine the economic impact this insect poses to the soybean crop in terms of direct yield losses. The 2003 growing season marked the third year of this study. The overall goal of this study is to examine the impact of the soybean aphid on soybean yield and to determine the level of infestation at which a foliar insecticide application is economically justified. Development of an economic threshold along with sampling criteria will allow soybean producers to make informed decisions regarding the importance of aphid damage and optimal use of control methods.