This study examines Chinese imperial polygamy under two aspects, as institution and actual practice. Institution refers to its existence as a set of rules and expectations, practice to the actual ways in which imperial people carried out polygamy as recorded in both historical and fictional sources. The key to the institutionalization of polygamy had to do with the idea that a ruler did not engage in polygamy because he wanted to, but because he had to in order to fulfill his role as Son of Heaven. He was obligated to extend the patriline and was as if following a hallowed directive. Practice had to do with what rules and expectations could not control or predict, including how a man justified his role as polygamist, his polygamous transgressions, and how he dealt with the main challenge to polygamous harmony, women's jealousy and rivalry.