This chapter examines attitudes toward vaccination through the lens of moral psychology, focusing on how moral convictions shape vaccine acceptance or resistance. While vaccines are a proven tool for preventing disease, hesitancy remains widespread and increasingly moralized. Drawing on theories of moral conviction, the chapter explains how individuals perceive vaccination not just as a personal choice but as a moral issue—seen as objective, universal, and independent of authority. Three studies conducted in Poland (N > 3,700) reveal that moralized attitudes toward vaccination reinforce both support and opposition, increase distrust or trust in institutions, and predict greater acceptance of coercive measures in line with one’s stance. The chapter also evaluates the effectiveness of moral reframing—presenting pro-vaccine messages in a way that aligns with the audience’s moral values (e.g., purity, care, social norms). Results show that reframing is effective, particularly among individuals who do not strongly moralize their views. However, strong moral convictions can render individuals resistant to persuasion. The chapter concludes with practical recommendations for crafting public health messages that appeal to diverse moral foundations, highlighting the importance of matching message content to audience values for greater communication effectiveness.