This investigation is a study of the marriages of the Castilian royal family during the reign of King Alfonso VIII and Queen Leonor. When they were married in 1169, the young king Alfonso obtained a victory over the Castilian nobility with his marriage, and he was able to protect his position as king with that marriage. For this reason, when they went to organize the marriages and betrothals of their sons and daughters, Alfonso and Leonor took care to find spouses of a similar matrimonial potential as the king had found with his marriage to Leonor. The marriage alliances, which were the potential of their children’s spouses, were influenced by the positive result of the marriage of Alfonso and Leonor, and for this reason the marriages of their children is reflective of the importance of his marriage to Alfonso as a king. A study, therefore, of the marriage alliances of their children allows historians to better understand the political magnitude of the marriage of Alfonso and Leonor to the royal couple themselves.Esta investigación es un estudio de los matrimonios castellanos reales durante el reino de Alfonso VIII de Castilla y su reina Leonor. Cuando se casaron en 1169, el rey joven Alfonso obtuvo una victoria sobre la nobleza castellana con su matrimonio, y él pudo proteger su posición como monarca con este matrimonio. Por esta razón, cuando organizaron los matrimonios y esponsales de sus hijos e hijas, el rey Alfonso y reina Leonor se encargaron de encontrar esposas de un potencial similar como el rey había encontrado con su reina. Las alianzas matrimoniales, que fueron posible en las esposas de sus hijos, fueron influenciados por el éxito del matrimonio real de Alfonso y Leonor, y de este modo las alianzas de sus hijos son un reflejo de la importancia de su matrimonio al reino de Alfonso como un rey. Un estudio, por consiguiente, de las alianzas matrimoniales de sus hijos permite a los historiadores entender mejor la magnitud del matrimonio del rey Alfonso y la reina Leonor.