Infants do not readily organize using form similarity: 6- to 7-month-olds familiarized with horizontal or vertical bars (filled rectangles) do not display a subsequent preference for a novel column versus row organization of X-O elements (Quinn and Bhatt, 2006 Journal of Experimental Psychology: Human Perception and Performance 32 1221-1230). In experiment 1, infants were familiarized with more complex bars composed of beads or crosshatches, and performance was again unsuccessful. In experiment 2, all three bar types were presented during familiarization and infants performed successfully, indicating that variability in pattern information depicting an invariant structure enhances the learning of perceptual organization. In experiment 3, we examined whether the manner in which variability is experienced (simultaneous versus sequential contrast) impacts this learning. One group of infants was familiarized with a single pattern containing the three different bar types (within-trial variability), and another was presented with the same three bar types, but with each appearing on a different trial (across-trial variability). Only the across-trial variability group performed successfully, suggesting that trial-to-trial change in local element information induced by sequential presentation is a significant factor in facilitating the learning of perceptual organization.