Most galaxies are thought to harbor a supermassive black hole (SMBH) at their center, with a mass of more than 106 Msun. During a major galaxy merger, two SMBHs will interact with a common environment as they sink to the center of the merging system. The black hole pair will eventually form a binary, emitting the most intense gravitational radiation in the Universe until they coalesce. Standard cosmological growth models have predicted that up to 10% of galaxies could contain black hole pairs at various stages of evolution, however the discovery of supermassive pairs in galaxies has been notoriously difficult. I will briefly review the astrophysical questions that the detection of supermassive pairs can address, and will detail several efforts to detect both electromagnetic and gravitational radiation from dual supermassive black holes.