Invasive vertebrate pests including mice cause significant environmental damage and agricultural loss of productivity. Current control and eradication methods have limited efficacy. A potential solution to this problem is the genetic modification of entire populations of wild mice to suppress their numbers. A CRISPR-Cas9 based gene drive is a genetic construct that promotes its own inheritance and can therefore spread through a given population. This is achieved by incorporating the components of the CRISPR-Cas9 system into the mouse genome where it can be inherited from one parent and subsequently copy itself to the wild type chromosome inherited from the other parent. This approach has the potential to eradicate invasive mice populations through addition of "cargo" genes that induce phenotypes such as sex-reversal, sterility, or embryonic non-viability leading to a population crash. CRISPR-Cas9 gene drives have so far only been shown to work effectively in a small number of species including flies, mosquitoes, and yeast. We have constructed a “split” gene drive in mice driven by a ubiquitous CMV promoter. Our data show that the gene drive system is able to effectively cut the wild type allele but is unable to copy itself, instead generating indels. Work is currently underway to produce a gene drive under the control of the germline-expressing VASA promoter which offers greater promise at effectiveness. This is the first attempt at developing CRISPR-Cas9 gene drive technology in vertebrates and provides an important first step towards assessing their potential for population suppression of invasive mice.