Despite Uganda’s progress in achieving an average immunization coverage of 90 percent, significant gaps remain in reaching zero-dose (ZD) and under-immunized (UI) children. A 2024 study by the Uganda Learning Hub focused on three high-risk communities in Mubende district to estimate the prevalence of ZD and UI children, understand barriers to immunization, and provide actionable solutions. The study revealed that 12.7 percent of children in these communities were ZD, with many born outside health facilities or cared for by non-biological guardians. Key barriers included negative health worker attitudes, caregiver knowledge gaps, cultural resistance, fear of side effects, and logistical challenges such as distance to health facilities. The findings emphasize the importance of targeted outreach, improving health worker attitudes, caregiver education, and strengthening health infrastructure and data systems to close the immunization gap and ensure no child is left behind.