This study analyzed the psycho-social and psycho-political variables that contribute to predict prejudice towards sex workers (PSW). A two-phase quantitative study with university students was carried out: phase one included an instrumental research oriented to the construction and evaluation of a scale of PSW; phase two consisted of an ex post facto study with simple retrospective design. After ratifying the psychometric qualities of the constructed scale, a multiple regression analysis was performed. In both PSW dimensions, authoritarianism and opposition to equality were two of the variables that most contributed to the prediction. Also, religion and ideological self-placement were included in the models.