Childhood immunization is one of the most successful and cost-effective public health interventions to date, preventing an estimated 2 to 3 million deaths every year and severe morbidity for millions more children from devastating diseases such as polio and the hepatitis B virus. Although there have been substantial gains in childhood immunization globally, coverage still lags in many countries, leaving millions vulnerable to disease. A particular challenge is on the demand side—low acceptance and uptake despite availability of vaccine supplies and services. Demand-side interventions target the barriers to acceptance and uptake, such as lack of awareness about the schedule and benefits, low prioritization of immunization, financial obstacles, or distrust in immunization. These interventions will only move the needle in the context of a functioning vaccine supply chain and effective health services. In this brief, Innovations for Poverty Action’s Path-to-Scale Research team has compiled the evidence for demand-side interventions to increase child immunization in low and middle-income countries (LMICs).