Background: Social capital, defined as the people one knows and the resources available through that network of people, has been a key variable in research examining the participation of women and underrepresented minority students in science, technology, engineering, and mathematics (STEM). This study focuses on two types of social capital: instrumental (concrete advice and resources) and expressive (emotional support and encouragement). The analysis of interviews with 55 White women and women and men underrepresented minority engineering undergraduate students shows how the instrumental and expressive social capital received from parents influenced their students' declaration of and persistence in the engineering major. Within this analysis, we considered students' transition to adulthood and the corresponding expectation that parents would still provide support but allow their children to independently determine their own paths. Results: Participants shared the advice they received from people in their social networks, with the majority of participants highlighting parents as a major contributor of instrumental and expressive social capital. Instrumental social capital was helpful in students' major declarations and offered them an opportunity to further develop their interests and aptitude in STEM as well as a pathway for obtaining an engineering degree. During the first year of their engineering major, students relied heavily on the expressive social capital of parents when considering whether to stay in engineering; parental encouragement of "you can do it" became a common resource. Conclusions: These findings offer nuance to explanations of social capital's influence on STEM degree major declaration and persistence, which often use deficit approaches. In highlighting the resources of social capital, especially expressive support, this work offers educators a new frame of reference for building upon the valuable advice offered by parents to their children completing engineering majors.