This book studies India's Universal Immunization Programme using National Family Health Survey-4 (2015-16) data. Assuming the ceteris paribus supply side constraints, this study tries to find out the factors that explain the underutilization of immunization services in India. Only then will the immunization coverage rate be augmented considerably by giving a big push to those predictor variables. It shows the effects of some selected demographics. It also presents the socioeconomic predictor variables on the likelihood of a child receiving immunization for six vaccine-preventable diseases. A qualitative data analysis complements the study. Immunization coverage rates increase with factors such as a mother's education level, mother's age, mother's exposure to mass media, mother's awareness about immunisation, antenatal care during pregnancy, wealth index, household electrification, mother's empowerment index, and caste/ tribe hierarchy.