The nuclear receptor superfamily comprises a group of transcriptional regulators involved in a wide variety of physiological responses. Rev-erb beta is a member of a growing subfamily of orphan nuclear receptors that bind DNA with high affinity either as monomers or as hetero- or homodimers. DNA bending assays, high-resolution footprinting, molecular modeling, and site-directed mutagenesis were used to analyze the structural features of the interaction between the DNA-binding domain (DBD) of the nuclear receptor Rev-erb beta and its DNA target sites. The results obtained point to the involvement of a carboxyl-terminal sequence adjacent to the second zinc finger of the Rev-erb beta DBD in protein-DNA interaction as a monomer or in protein-DNA and protein-protein interactions as a homodimer. They also provide insight about the amino acid residues directly involved in protein-protein contacts.