This report provides the data collection framework to assess, from a regional/territorial perspective, the impacts of Third Country Nationals (TCNs) in European rural and mountain areas. The data collection framework, hereinafter MATILDE Matrix, provides guidance for the multilevel (EU-aggregate, national, regional and local level) and multidimensional (social, economic, territorial) impact assessment to be conducted in Work package 3 (Social impact assessment of migration), Work package 4 (Economic impact assessment of migration) and Work package 5 (Implementation of MATILDE toolbox in rural and mountain case study regions). The MATILDE matrix combines migration-specific indicators with indicators on economic growth, employment, access to services, and indicators that consider the urban/rural and mountain linkages and the transformations brought about in rural/mountain regions as a result of migration processes.