Definitions Verification is the process of confirming the claims of communities to have met the criteria for ODF status. Certification is the official confirmation and recognition of the ODF status of communities. Verification of communities claiming to be ODF (open defecation free) and certification of these communities are key stages in CLTS follow up and vital for quality assurance and sustainability of collective behaviour change. Carrying out follow up, verification and certification at scale is not an easy task. With more and more national governments adopting CLTS as their key approach to sanitation and including it in their policies, there is a need for streamlined guidance on monitoring and on how to conduct verification and certification.