This chapter presents the first empirical stage of a project that consists of two steps: the delimitation of Functional Urban AreasFunctional Urban Areas and their typology in order to identify the inner peripheriesInner peripheries in PolandPoland. We first briefly present the state of knowledge on the regional development disparitiesDevelopment disparities in the country. After that, we describe how we divided the territory of Poland into 413 Functional Urban Areas (FUAs) based on the inter-municipal movement of population: commuting and mirgration. Following a discussion of the resulting division of Poland into FUAs and confronting it with the administrative division of the country, we use the FUAs as the building blocks for the typology of territories based on their multidimensional core-peripherality characteristics, which, in turn, were used to identify territories that we label as inner peripheries. The classification of FUAs and the identification of two types of inner peripheries based on a set of 47 indicators is described in the third section of the chapter and then confronted with the previous studies on the regional development disparities in Poland. The final part of the chapter outlines how we selected four FUAs classified as inner peripheral ones for further investigation as case study areas and provides a description of these areas.