The objectives of this article were to investigate to which extent and in what ways persons influence students' choice of science, technology, engineering, and mathematics (STEM) in tertiary education, and to assess the suitability of an analytical framework for describing this influence. In total, 5,007 Norwegian STEM students completed a questionnaire including multiple-choice as well as open-ended questions about sources of inspiration for their educational choice. Using the conceptualisation of "significant persons" suggested by Woelfel and Haller, the respondents' descriptions of parents and teachers are presented in order to elaborate on the different ways these significant persons influence a STEM-related educational choice. Parents engaged in STEM themselves are "models", making the choice of STEM familiar, and they help youngsters define themselves through conversation and support, thus being "definers". Teachers are models by displaying how STEM might bring fulfilment in someone's life and by giving pupils a positive experience with the subjects. They help young people discover their STEM abilities, thus being definers. Celebrities are reported to have minor influence on STEM-related educational choices. Both qualitative and quantitative analyses indicate that "interpersonal relationships" are key factors in order to inspire and motivate a choice of STEM education. Implications for recruitment issues and for research on interpersonal influence are discussed. It is suggested that initiatives to increase recruitment to STEM might be aimed at parents and other persons in interpersonal relationships with youth as a target group. (Contains 4 tables and 3 figures.)