Low participation of women in Computer Science (CS) has been documented in some countries. Since this phenomenon occurs in the Computer Science and Informatics Department at the Universidad de Costa Rica, we decided to investigate if there were gender differences in some factors, both motivating and inhibiting students to enter the field. Our main purpose was to see if those differences could help find factors influencing the imbalance of female participation. Both graduate and undergraduate populations were investigated. It was found that there were differences by gender in both populations. As a consequence of the knowledge of the field acquired during the permanence in the CS program and professional experience, both men and women change, although differently, their perceptions.