The papacy has often resembled a secular European monarchy more than a divinely inspired institution. Roman pontiffs bestowed great wealth on their families and forged strategic alliances with other powerful families to increase their power. Pope Alexander VI (Rodrigo Borgia), for example, forced his daughter Lucrezia into a series of marriages for political reasons. When her marital alliance was no longer advantageous, as was the case in her second marriage, her husband was brutally murdered. Many papal families also intermarried in hopes of forming a hereditary papacy; at least two members of the Fieschi, Piccolomini, Della Rovere, and Medici families served as pope.

Papal families since the early history of the church are fully covered in this comprehensive work. Genealogical charts graphically show the descendants of the popes, presenting in many cases the interrelationships between the papal families and their relationships with many of the leading families of Europe. Detailed histories examine the impact of the papacy on each pope's family and how each influenced the history of the church.