Compared to most insects whose mitochondrial genome arrangements are extremely conserved, the Psocodea (lice and relatives) have the highest rates of genome rearrangement amongst insects and one of the highest of any animal group. This diversity of genome arrangements within a relatively small clade (approx. 10’000 described species) makes lice a perfect system in which to examine the evolution of genome rearrangements, the factors which predispose genomes to rearrange and their utility in systematic studies. The free-living relatives of lice, the Psocoptera (sensu lato) have fewer rearrangements than the louse groups once classified as Phthiraptera. The largest suborder Psocomorpha is defined by a major rearrangement of protein coding genes and a minor rearrangement of tranfer RNA genes. Trogiomorpha has a range of rearrangements from early diverging members with the groundplan arrangement to derived members with multiple major and minor rearrangements. The Nanopsocetae (including the parasitic louse groups) have extreme rates of genome rearrangements and the utility of genome architecture in resolving this phylogenetically intractable set of taxa will be discussed.