A total of 116 subjects participated in the study. All subjects had Spanish citizenship and were included in one of four groups of 29 persons each: offending women, non-offending women, offending men, and non-offending men. These groups were similar in age, socio-cultural level, and place of residence. The female offender group was composed of inmates with Spanish citizenship in the women's unit of the Centro Penitenciario Tenerife II. The research followed a 2x2 factorial design, with two independent variables: gender and criminality. Dependent variables were perspective-taking, alternative thinking, causal thinking, consequential thinking, and means-end thinking. Controlled variables were age, educational level, citizenship, and place of residence. The five questionnaires used in the study were developed by Bethencourt (1989) to measure socio-cognitive skills, following Spivack et al.'s (1976) formulations. Each of these instruments is composed of 15 problem situations about which subjects give their opinion. Offending women scored significantly higher than non-offending women on causal thinking and on consequential thinking as well as alternative thinking, although the latter two variables did not rise to a significant level. Female offenders were less skilled than female non-offenders in perspective-taking and in means-end thinking, but not significantly. These findings suggest that factors other than the ones measured in this study are more important in the social rehabilitation of female offenders. Offending men scored significantly higher than non-offending men in perspective-taking and, although not to a significant level, in causal thinking, consequential thinking, means-end thinking, and alternative thinking. Women offenders scored significantly higher than offending men in consequential thinking and in alternative thinking. Generally, women scored significantly higher than men in alternative thinking, consequential thinking, and means-end thinking. Thus, results show that gender was more important than criminality in determining a subject's socio-cognitive skill level. 5 figures and 41 references