Technical Abstract: Integrated crop-livestock systems are inherently more complex than the current model of specialized agricultural production in industrialized countries with clear separation of crops and animals. A movement towards integrating crops and livestock will have impacts on soils and the environment; the key is to understand whether those impacts will be negative or positive. Literature is reviewed on the soil physical responses to various components of integrated crop-livestock systems. Response categories were separated into effects on (1) rooting environment (soil aggregation, bulk density, and penetration resistance), (2) water availability (soil water content and water infiltration), and (3) nutrient availability (soil organic matter and soili-profile stratification of organic matter and nutrients). Both negative and positive effects of introducing animals onto cropland are possible. With high soil moisture and high stocking rate, animal trampling can compact soil and disrupt the soil surface sufficiently to cause a reduction in subsequent plant growth and contribute to increased water runoff and nutrient loss during intense rainfall events. However, well-managed, integrated crop-livestock systems should create opportunities to avoid continuous stocking of animals on perennial pasture, thereby distributing the stress of animal traffic onto a greater land area and across different times of the year. More research is needed to understand whole-system interactions in integrated crop-livestock systems, not just direct effects of isolated components, such as (a) forage-crop rotations without animals or (b) animal treading effects in isolation of long-term cropping system evaluation.