The evaluation of public programs and interventions has a long and rooted tradition, especially in the North-American and Anglo-Saxon contexts. Paradigms, methodologies and methods are well studied in the literature. Despite the accumulated knowledge little is known about the diffusion in the context of the Italian social services, but most of all the way in which the evaluation is operationalised. Indeed, the term evaluation may involve a very wide, and most of the time unknown, set of options, and sometimes what is called evaluation, in reality it is not. The aim of the paper is to present a summary of the paradigms and methodologies through which an evaluation can be carried out, stressing the difference between qualitative and quantitative analysis. Moreover, the paper presents some results derived from a research on the evaluation methodologies and methods used in the context of the Health Plans in the Emilia Romagna Region.