Perhaps one of James Gibson's most important insights was that certain changes over time at the edges of a moving object can serve as invariant information for the boundaries of that object (Gibson, Kaplan, Reynolds, & Wheeler, 1969). Recent work suggests that the class of changes that can define the boundaries of a moving object extend well beyond the original suggestion of accretion and deletion. Changes in color, shape, and location of texture can also be used to perceptually define the boundaries of a moving object (Shipley & Kellman, 1993). Furthermore, both the spatial and temporal density of these changes appears to play important but independent roles in the perceptual process, which we refer to as spatiotemporal boundary formation (SBF). However, relatively little is know about how SBF interacts with other perceptual processes. There has been some work on perception of depth in accretion/deletion displays that suggests the perception of depth may be effected by the motion of texture elements relative to boundaries (Yonas, Croton, & Thompson, 1987). Furthermore, Lee (1970) has suggested that the visual system can utilize the disparity between contours defined by accretion/deletion to perceptually localize an object in depth (Lee refers to this information as "kinetic disparity"). Here, we explore Lee's suggestion by studying how spatial variations in changes over time affect stereopsis based on the disparity of spatiotemporally defined boundaries.