PURPOSE The reduction of immunization errors through the use of age-specific alerts within the electronic medical record (EMR) and mandatory interactive education for prescribers is described. METHODS A health system-wide initiative was implemented at an academic pediatric hospital to reduce the number of immunization errors. The preimplementation period (January 1-December 31, 2013) involved a baseline review of adverse drug events (ADEs) reported through a voluntary event reporting system to determine the number and types of immunization errors. During the prescribing phase of the medication-use process, 57% (43 of 75) of errors occurred. First, age-based restrictions were implemented within the EMR. This was followed by mandatory immunization education for all prescribers working in the primary care network. Data collection included all reported vaccine errors within the voluntary event reporting system and completion rates of education by physicians, nurse practitioners, and medical residents. RESULTS During the seven-month postimplementation period (January 1- July 31, 2014), prescribing events decreased from 57% to 25%. Following implementation of age-specific immunization alerts and mandatory prescriber education, the hospital went 175 days without a vaccine ADE. CONCLUSION The implementation of age-specific alerts within the EMR and mandatory prescriber education decreased the number of immunization errors within a pediatric health system.