The rate of recombination is a key parameter in evolution and genetics. Recombination governs the fidelity of the meiotic process, shapes the fates of new alleles in populations, and weighs on hypotheses for the origin and maintenance of sex. Despite its biological importance, observed variation in recombination rate among individuals and between species remains poorly understood. Classical genetic studies have demonstrated that intra-specific recombination rate variation is controlled by a complex genetic system, but the precise genetic variables and the details of their organization within genomes remain largely unknown. Toward this goal, we are harnessing the power of the house mouse model system to study the genetic basis of intra- and inter-specific recombination rate variation. Using immunohistochemical methods for measuring genome-wide recombination rates, we have documented significant differences in the total amount of recombination per meiosis between males from 3 sub-species of house mice (Mus mus castaneus, M. m. domesticus and M. m. musculus; P < 0.0001 for all comparisons), with lesser, although still statistically distinct differences among independent wild-derived inbred strains of M. m. domesticus (n=2; P < 0.001). These findings confirm the presence of substantial divergence and polymorphism for recombination rate in wild populations of house mice. Crosses between highly diverged M. m. castaneus and M. m. musculus wild-derived inbred strains are currently underway. Our objective is to measure genomic recombination rates in ~200 male F2 mice from this cross in order to conduct a genome-wide analysis to further characterize the genetic factors contributing to natural variation in recombination rate.