The way in whch segments of DNA find each other to initiate site-specific genetic recombination has been explored. Two pathways have been defined; random collision and one-dimensional sliding along DNA. The choice between these two pathways reflects differences in the nucleosome structure of the recombining sites caused by recombination proteins. The interaction of one recombination protein with sequences not involved in recombination has been examined. A consensus sequence for the binding of this protein has been deduced. Methylation protection experiments indicate that binding of this protein is unusual in that the primary contacts involve residues of the protein with the minor groove of the double helix.