Project ImpactPP – Innovation in Public Policies Impact Evaluation seeks to identify and test groundbreaking impact evaluation methods in an eminently operational and empirical perspective. To this end, it will test and innovative impact Evaluation methodological approach focused on the PT2020 Investment Priority 08 and its corresponding social housing support operations, based on the triangulation of three base-methods (Policy Scientific Approach; Qualitative Comparative Analysis; and Contingent Appraisal Method), thereby seeking to build an impact methodology regulated by the «theory-based evaluation» principle, maximizing the combined potential of three crucial theories in contemporary Public Policy Science: Theory of Programming, Theory of Causation and Theory of Complexity.