The lack of females entering STEM careers is well documented. Reasons for the gender gaps at all stages of the educational pipeline include both internal factors such as self-concept and external factors such as the influence of parents, media, and educators. Using latent growth curve analysis and nationally representative longitudinal survey data, this study compares differences in the relationship between a critical external factor (perceived early parental support), student mathematics and science achievement trajectories, and persistence in STEM career by gender. Mathematics and science trajectories were positively related to STEM career persistence for males and females. Perceived early parental support was related to growth in mathematics achievement for males but not females. There was no relationship between early perceived parental support and growth in science achievement for either males or females. These findings indicate differences in the relationship between parental support, achievement, and career persistence depending on content area and gender.