This study explored how interpersonal relationships may affect the development of interest in science from college students' perspectives. Semi-structured interviews with 24 college students were conducted and analyzed. The findings indicated that interpersonal relationships could start and sustain students' interest in science; negative interpersonal relationships could cause students to lose interest in science. Four qualities were often associated with the interest-raising relationships: (1) The influential figure was perceived as having a positive relation with science. (2) The influential figure actively mediated the relation between the student and science. (3) The influential figure conveyed as well as created positive emotions about science when he or she did science with the student. (4) The influential figure and the student had a personal relationship characterized by caring, sharing, and/or launching. Interest-lowering relationships lacked these qualities. Implications for education and future research were discussed.