Effective monitoring, epidemiological assessment and evaluation are necessary to achieve the aim of interrupting LF transmission. This manual is designed to ensure that national elimination programmes have available the best information on methodologies and procedures for monitoring MDA, appropriately assessing when infection has been reduced to levels where transmission is likely no longer sustainable, implementing adequate surveillance after MDA has ceased to determine whether recrudescence has occurred, and preparing for verification of the absence of transmission. The manual provides general guidance to national programmes; relevant background information on technical issues is contained in the annexes. As real-life situations may not correspond to predefined categories, consultation with WHO and experts is recommended in complicated situations.