Drawing on professional socialization theory, this study examined how immersive experiences as science outreach educators in K-12 schools influenced the career paths and professional identities of science and engineering graduate students. Semi-structured interviews with 24 outreach program alumni revealed that school outreach experiences provided three important elements of professional socialization: specialized knowledge and skills needed to succeed in the profession; direct involvement with the profession's activities, colleagues, and personal meanings; and personal investment in the role and status of the profession. Outreach involvement exerted different patterns of influence on career paths. For some students, outreach participation confirmed career intentions, and provided knowledge and skills needed to succeed in the chosen path. For others, participation facilitated a change in career direction by providing low-risk opportunities to explore an alternate career and discover new career options. (Contains 1 table and 1 figure.)