Objective: Given poor use of recall in primary care practices, we compared outsourced versus office-based recall systems. Study Design: From 2011 to 2013, we enrolled 87 individual Arkansas providers in distinct practices treating their own patients <24 months of age which were randomized to usual care (A), office-based (B), or outsourced (C) recall groups. Results: At the end of study, recall activity was 19.4%, 55.0%, and 92.6% for Groups A, B, and C, respectively (B and C vs A: P < .001). Only 68 Group B patients were identified as needing immunizations versus 826 in Group C. The majority of successful contacts were made through mobile phone (41.3%) or text message (32.6%). The total cost per practice per week was significantly lower for Group C versus Group B ($39.50 and $53.00, respectively; P = .004). Conclusions: With limited electronic health record use, an outsourced recall system is more sustainable and less costly than an office-based system.