The recombination mechanisms that deal with double-strand breaks in organisms as diverse as phage, bacteria, yeast, and humans are remarkably conserved. We discuss conservation in the biochemical pathways required to recombine DNA ends and in the structure of the DNA products. In addition, we highlight that two fundamentally distinct broken DNA substrates exist and describe how they are repaired differently by recombination. Finally, we discuss the need to coordinate recombinational repair with cell division through DNA damage response pathways.