The aim of this paper is to make a sociological study of the Castilian episcopacy in the reign of Enrique IV (1454-1474). We will analyse differents sociological aspects of the bishops, such as their number, appointment age, social and regional origins, education or their pre-episcopal careers. The ultimate goal is to move towards a better knowledge of the bishops as an ecclesiastical and power elite in late medieval Castile. [ABSTRACT FROM AUTHOR]