In 2013, during the 66th session of the Regional Committee of the World Health Organization (WHO) South-East Asia Region (SEAR), the 11 SEAR countries* adopted goals to eliminate measles and control rubella and congenital rubella syndrome by 2020† (1). To accelerate progress in India (2,3), a phased§ nationwide supplementary immunization activity (SIA)¶ using measles-rubella vaccine and targeting approximately 410 million children aged 9 months-14 years commenced in 2017 and will be completed by first quarter of 2019. To ensure a high-quality SIA, planning and preparation were monitored using a readiness assessment tool adapted from the WHO global field guide** (4) by the India Ministry of Health and Family Welfare. This report describes the results and experience gained from conducting SIA readiness assessments in 24 districts of three Indian states (Andhra Pradesh, Kerala, and Telangana) during the second phase of the SIA. In each selected area, assessments were conducted 4-6 weeks and 1-2 weeks before the scheduled SIA. At the first assessment, none of the states and districts were on track with preparations for the SIA. However, at the second assessment, two (67%) states and 21 (88%) districts were on track. The SIA readiness assessment identified several preparedness gaps; early assessment results were immediately communicated to authorities and led to necessary corrective actions to ensure high-quality SIA implementation.