Life for a foot soldier frequently involves marching while wearing a uniform, boots, and interceptor body armor vest (IBA) and also carrying a backpack and rifle. Additionally, soldiers may traverse various terrains from smooth to rough, from vegetated to barren, from steep inclines to varying angles of cross slopes. The study presented here is new and unique. It determines the lateral stability of a person walking along a cross slope using a formula which is based on the inverted pendulum. Those who participated in this study walked along cross-slopes (0, 5 or 10 degrees) while wearing backpacks loaded at various levels (low, middle or high). The final results of this particular investigation, however, indicate that neither load position nor cross-slope angle produced significant effects for lateral stability within an alpha of 0.05 for the participants accustomed to backpacking.