Young women remain underrepresented among engineering bachelor's degree holders. While there is a relatively large body of extant research on the many factors that curtail young women's interest in pursuing engineering, less is known about high school girls who are on an engineering pathway. Therefore, this study focuses on a select group of precollege young women who express a strong interest in engineering. Specifically, informed by theories of gender as a social system and previous empirical research, this mixed-methods study explores the constellation of significant actors within the daily lives of these young women, to understand from whom and how they are supported in pursuing this gender-atypical field, and simultaneously, from whom and how they are discouraged. To do so, the researchers analyzed survey and interview data from a sample of diverse high school girls who participate in the Society of Women Engineers' (SWE) SWENext programme. Quantitative results indicate that young women report high levels of encouragement from most sources, including parents, teachers, and other young women. However, across various peer contexts, they receive much more support from other young women than from young men. Qualitative results further reveal that parents and teachers stand out in young women's recollections of encouragement, often through advocating their participation in engineering activities or providing mentoring support. In contrast, young men in engineering spaces were recalled as particularly discouraging of their engineering participation, by socially or physically excluding them or refusing to provide recognition. Implications for future research and practice are discussed.