Advocacy efforts are needed to help countries align with international frameworks when improving infant and young child feeding (IYCF) policies. This article uses contribution analysis (CA) and develops a contribution story to evaluate the impact of the Alive & Thrive/UNICEF initiative in seven Southeast Asian countries, identifying the extent to which policy objectives were achieved and the drivers of policy change. Using these two evaluation approaches, CA and developmental evaluation, confirmed that the advocacy efforts of this initiative made progress in IYCF policy in Southeast Asia.