BRCA2 is a tumor suppressor that functions in homologous recombination, a key genomic integrity pathway. BRCA2 interacts with RAD51, the central protein of recombination, which forms filaments on single-stranded DNA (ssDNA) to perform homology search and DNA strand invasion. We report the purification of full-length human BRCA2 and show that it binds to ~6 RAD51 molecules and promotes RAD51 binding to ssDNA coated by replication protein A (RPA), in a manner that is stimulated by DSS1.