We are generally interested in genomic stability and chromosome evolution, especially how these are impacted by mobile DNA elements. We have a special interest in molecular mechanisms mobile elements capable of moving between positions in the genome called transposons use to limit damage to the host and maximize the process of horizontal transfer. The bacterial transposon Tn7 and Tn7-like elements are special in this regard, possessing one targeting pathway that recognizes a unique “safe” site in the chromosome and a second pathway that maximizes horizontal transfer by specifically targeting transposition into mobile elements capable of cell-to-cell transfer. These under-appreciated elements fall into at least 22 distinct families and appear to reside in 10-20% of all sequenced bacteria, where they contribute to antibiotic resistance, pathogenicity, bacterial host defense and a variety of other functions. In addition to providing an important window into how bacteria evolve new functions, they also provide important tools for genomics.