Despite years of health and medical advancement, children still suffer from infectious diseases that are vaccine preventable. India reacted in 1978 by launching the Expanded Programme on Immunization in an attempt to reduce the incidence of vaccine-preventable diseases (VPDs). Although the nation has made remarkable progress over the years, there is significant variation in immunization coverage across different socioeconomic strata. This study attempted to identify the determinants of wealth-based inequality in child immunization using a new, modified method. The present study was based on 11,001 eligible ever-married women aged 15–49 and their children aged 12–23 months. Data were from the third District Level Household and Facility Survey (DLHS-3) of India, 2007–08. Using an approximation of Erreyger’s decomposition technique, the study identified unequal access to antenatal care as the main factor associated with inequality in immunization coverage in India.