As more countries transition from paper-based to electronic immunization registries (EIRs) to collect and track individual immunization data, guidance is needed for successful adoption and use of these systems. Little research is available on the determinants of EIR use soon after introduction. The BID Initiative published an observational study assessing the determinants of facility health care workers’ use of new EIRs in Tanzania and Zambia. The results highlight the importance of organizational and behavioral factors in explaining sustained EIR use. Read the full manuscript in Global Health: Science and Practice.