This study investigates the underrepresentation of women in science, technology, engineering, and mathematics (STEM) occupations from the aspect of earning differentials. Using a national data source that tracked college graduates' work experiences over a ten-year time frame post-bachelor's degree, this study examines longitudinally the gender-based earning gaps of college graduates in STEM fields, and compares the earning differentials between STEM and non-STEM occupations. The findings indicate a significant departure between the earning profiles of men and women within the first ten years of employment. Further, findings indicate that women in STEM occupations experienced multiple earning penalties concurrent with their growing family obligations. To increase the representation of women in STEM fields, interventions are called for to encourage a family-friendly workplace that is open to and supportive of women managing a home and career. Also, incentives are needed to support women's continuation to graduate education as a means to increase their human capital and to level their earning power.