The majority of cultivars in current commercial sugarcane breeding programmes trace back to a few key interspecific hybrids that were developed during the early 1900s. Sugarcane breeders have expressed concerns about the narrow sampling of ancestral clones in modern sugarcane breeding programmes, and this concern has prompted periodic attempts at so-called ‘base-broadening’ programmes. This chapter begins by providing an overview of sugarcane germplasm collections and then describes introgression-related research and breeding efforts focused on the use of Saccharum spontaneum, Erianthus and other species. It emphasizes the difficulties and challenges that need to be overcome in order to achieve successful outcomes from introgression breeding. Finally, a few possible future directions are considered.