Research on arthropod genetics and development has added much to our understanding of animal evolution. While this work has mainly focused on insects, a growing body of research on the less studied myriapods and chelicerates is providing important new insights into arthropod genomics and development. Multiple chelicerate lineages have a high incidence of gene duplication, which is suggestive of large-scale and even whole genome duplications. Furthermore, the duplication and divergence of genes is associated with the evolution of appendage morphology and other phenotypes in chelicerates and myriapods. Recent studies of these arthropods have also helped to understand the evolution and development of segmented bodies. Further research on chelicerate and myriapod models as well as species from other orders of these subphyla has great potential to expand our understanding of the evolution of animal genomes and development.