ABSTRACT: Territorial sustainability is introduced in the discussion of naturbanization, namely to regulate urban expansion processes and to frame the analysis of population dynamics, urbanization and urban sprawl in rural areas of Northern Portugal integrated in or near the Peneda-Gerês National Park (PNPG). These dynamics relate to changes that have been re-occurring over the last fifteen years spurring shifts in land use patterns, urban settlements and economic development trends. Two municipalities partially comprised within the National Park were selected as case studies for deeper insight on the urbanization trends as measured by development control indicators and motivations to live in PNPG, obtained through surveys on life histories. The study shows some evidence of naturbanization and counterurbanization processes. Concluding remarks on policies and strategies show that the impacts of naturbanization seem to depend largely on the degree of interregional disparities and the specific territory at stake.