The self-efficacy questionnaire of Soto (1990) was validated in Mexican youngsters, evaluating 500 university students aged 18 to 25 years old, of both sexes and shifts (morning and afternoon), from the city of Toluca, Mexico. By means of factor analyses with varimax rotation, four out of eight factors were obtained: pertaining to games-sports, problem solving, social prestige and family. A proportion of 58.363% of the variance is explained, and Cronbach’s Alpha for internal consistency has a value of 0,7633. Additionally, the results obtained by sex and by shift in which the subjects attend to university lectures are analyzed and discussed. It is suggested that self-referring thought should be studied further, since this influences the individuals’ behavior.