Objective: To evaluate the impact of a campus-based breastfeeding support campaign grounded in the Theory of Reasoned Action. Participants: Seventy-eight students and employees. Methods: An online survey was administered pre- and post-campaign to measure attitudes, subjective norm, normative and behavioral beliefs, intention, knowledge, and awareness. Regression analyses identified the most influential factors for intention to support breastfeeding on campus at both times. Paired sample t-tests compared changes over time. Results: Attitudes, but not subject norm, had a significant impact on intention to support breastfeeding on campus at both times (p < 0.01). Subjective norm improved over time (p = 0.04), whereas changes to attitudes, normative and behavioral beliefs, intention, and knowledge were small and mostly not significant. Participants gained awareness that a lactation space is available on campus (p = 0.034) and that students can be excused from class to pump (p = 0.005). Conclusions: Future campus-based efforts should target breastfeeding attitudes, knowledge, and awareness of breastfeeding supports.