While many biologists tend to think of individuals within a species as having very similar genomes there is growing evidence for major differences in the structure of genomes in different individuals of the same species. This structural genomic variation includes insertion/deletions, inversions and translocations. The insertion/deletions include examples of copy number variation (CNV) where different individuals possess different copy numbers for the same sequence and presence-absence variation (PAV) where some individuals contain a sequence while others lack this sequence. In collaboration with Patrick Schnable and [Jeffrey Jeddeloh] we documented extensive structural variation among maize inbreds. There are numerous examples of CNV and PAV among different maize genotypes. Further research on structural variation in collaboration with Candice Hirsch has utilized a variety of approaches to further understand the sources and impacts of structural variation in crop genomes.