Insects and weeds interact and affect not only each other, but also the efficacy of their respective management tactics. Field studies were conducted in 2003 at two locations in Nebraska (Lincoln, Concord) to examine the effects of early season insect defoliation of soybean and the increasing duration of weed interference on soybean growth, development, and weed management. A naturally occurring population of weeds was allowed to compete with the soybean crop for increasing length of time, and at three defoliation levels (0%, 30%, 60%). Within each defoliation level, weeds were removed at V2, V4, V6, R3, R5 stages of the crop. There were also season-long weedy and weed free treatments. Results indicate that there was 2.3 times more pods, 2.8 times more biomass, and a greater number of branches in undefoliated compared to 60% defoliated soybean. There was also an increase in specific leaf area in defoliated soybean indicating production of thinner leaves. The Critical Time for Weed Removal (CTWR) occurred earlier by as much as 13 days in highly defoliated soybean compared to the undefoliated crop.