On November 15, 2023, MOMENTUM Routine Immunization Transformation and Equity held a learning exchange webinar to discuss targeted assessments for identifying zero-dose and under-immunized children. The exchange focused on the use of some of these methods, including LQAS (lot quality assurance sampling) and cluster surveys, drawing from experiential knowledge from colleagues in two countries using these techniques, as well as reflections from WHO on how these approaches can be used as part of “The Big Catchup.”