The authors have carried out a research that proposes a critical review of the indicators and methods developed by the National Strategy for Inner Areas (SNAI), through the Principal Components Analysis (PCA) and using the R software. The research aims to obtain a classification more coherent with the characteristics of Sicily and more useful in supporting local development. The research results confirm that further and new indicators are needed to classify inner areas, in order to develop more effective policies for coping with Sicily’s peripheral condition.