The Guidance on Selection and Use of One Health Operational Tools [manuscript in preparation] was developed by the WHO South-East Asia Regional Office, in collaboration with the Human-Animal Interface Unit from WHO Headquarters. While mainly directed towards Agency and Ministry officials responsible for One Health, WHO regional and country offices, other Quadripartite organizations and partner agencies, this document can also be used by anyone interested in One Health initiatives. The document offers an overview of each tool, including their standard procedure, use, and key outputs, to optimize the implementation of these tools at the country level. For this purpose, the guidance provides an algorithm for a recommended sequence in which to use each tool, which can be applied to each country’s individual context.