Sclerotinia sclerotiorum (Lib.) de Bary is among the world's most successful and omnivorous fungal plant pathogens, with a host range of greater than 400 plant species. Despite decades of dedicated effort, resistant germplasm is still lacking in economically important crops. As an exemplar of soilborne pathogens and necrotrophic pathogenesis, S. sclerotiorum is a model for development of asexual, persistant propagules, somatic compatibility, and sexual sporulation. It is also central to a group of Ascomycetes with poorly known evolutionary relationships. We foresee control measures on several scales, e.g., blocking pathogen-plant signaling, defeating key pathogen developmental stages; or maintaining a broad base of genetic resistance against a range pathogen genotypes. These strategies could also be effective against closely related species. In the longer term, we see comparative genomics as tool for getting at key processes controlling genetic stability in populations, basic principals of pathogenesis in comparisons among other fungi, and better resolution of the Ascomycete branches (> 30, 000 species) of the Tree of Life.