Vaccinations provide protection against deadly diseases and children are scheduled to receive many immunization injections before the age of six. However, painful procedures, such as immunizations cause negative short- and long-term consequences for children. The Gate Control Theory of Pain suggests that physical interventions may be helpful, but they have not yet been validated as an effective intervention to manage children’s acute pain. This randomized trial examined the effectiveness of the ShotBlocker®, a physical intervention designed to decrease children’s injection pain, in a sample of 89 4- to 12- year-old children receiving immunizations at a pediatric practice. An ANOVA revealed no significant effect of treatment group (Typical Care Control, Placebo, and ShotBlocker®) on any measure of child distress. Clinical and theoretical implications are discussed.