The underrepresentation of women in engineering is a significant concern. This study applies the social cognitive theory and the social career cognitive theory (SCCT) to investigate gender differences in engineering career choices. We examined reasons given by 19 systems engineers and 330 undergraduate engineering students for choosing engineering and categorizing them according to SCCT themes. We compared the distribution of reasons across themes and categories by career stage and gender. For engineers, the category <i>self-efficacy</i> correlated significantly with <i>challenges and opportunities</i> and <i>current job suitability</i> categories, and women engineers cited challenges mainly with work-life balance and the gender glass ceiling. Undergraduate students cited personal reasons more frequently than environmental ones, with behavioral reasons being the least common. The extended SCCT model includes the categories <i>challenges and opportunities</i> and <i>current job suitability</i> within the behavioral theme, with the latter pertaining specifically to career retention. This research the set of provides insights into gender-dependent engineering career choice and retention by expanding the set of SCCT categories.