The shortage of STEM (science, technology, engineering, and mathematics) professionals worldwide calls for research to identify social forces that can foster student career interest in this domain. In this study, we examined the underlying structure of middle school student STEM career interest and the role of their parents' STEM-specific behaviors in explaining this interest. Students (N = 488) reported their interest in eighth grade (M[subscript age] = 14.48 years), while parental data were collected approximately 15 months earlier. Parents (N = 488) reported on their encouragement of their child's STEM interest, provision of STEM materials for the child, and their own participation in STEM activities. Student grades in STEM school subjects were collected at the end of seventh grade. The findings suggest that in this age, students differentiate between their interest in science and engineering-technology-oriented career activities. Boys showed higher STEM interest than girls but only in the engineering-technology domain. Prior STEM school achievement predicted student science interest but not engineering-technology interest. After controlling for student gender and STEM achievement, the overall parent STEM support predicted both types of STEM interest, equally for boys and girls. However, parents reported more STEM-specific practices in case of sons than daughters. The results are discussed in the framework of the ontogeny of children's STEM vocational interest and previous findings on the gendered socialization in STEM within the family. Implications for interventions and curricula in the STEM domain are also discussed.