The past thirty years have seen great advances in theoretical and experimental population genetics. The neutralist-selectionist debate has given way to a general consensus that stochastic, selective, and demographic forces all play important roles in patterning genetic variation. An important and open question remains, however, how to efficiently use genomic patterns of variation within and between species to identify genes and genomic regions that are the targets of natural selection. In particular, how does one disassociate the effects of demography (population growth, migration, bottlenecks) from those of natural selection? We collaborate extensively with experimentalist and theoreticians in developing tools for addressing these questions and applying them to novel and interesting data sets.