Eight months after training, only 4 of 11 practices had implemented recall using CIIS: 3 practices recalled children ≤2 years of age, and 1 practice recalled adolescent girls for human papillomavirus vaccine. Initiation barriers included lack of awareness of baseline immunization rates, distrust in the accuracy of CIIS-generated data, and perceived difficulties recalling adolescents. Having unrealistic expectations about recall effectiveness was a barrier to sustainability. Strategies that facilitated recall included having a dedicated staff person for recall efforts and recalling children ≤2 years of age. Most key informants viewed population-based recall conducted by public health departments or schools as an acceptable alternative to provider-based recall.