It is well known that the field of engineering faces an urgent national need to increase both the number and diversity of graduates. This constructivist grounded theory study contributes to this national effort by presenting a conceptual model describing the ways in which fictive kin (" like family") influence the academic and career decisions of engineering undergraduates who are first-generation college (FGC) students. While much is known about the challenges and barriers FGC students generally face in higher education, very little is known about the experiences of FGC students majoring in engineering. The case for considering FGC students as an at-risk and underrepresented group in engineering is particularly compelling considering common characterizations of the field as a" closed club" with associated" occupational inheritance." Undergraduate participants identified professors, research advisors, engineering student services coordinators, peers, peer-led organizations, minority and women engineering programs, undergraduate teaching assistants, living learning communities, engineering fraternal organizations, and pre-college summer programs as serving in fictive kin roles that contributed to their (1) sense of belonging in engineering;(2) confidence for majoring in engineering;(3) persistence; and (4) development of engineering-related networks. This paper makes recommendations for the engineering education community to promote inclusivity and diversity in the field by recognizing and building upon the existing roles individuals and programs play in the academic and career decisions of FGC students majoring in engineering.