Agenda setting and constructivism have established a very close relationship since the first publications on the transformation of an issue into a problem at the beginning of the 20th century. Why a problem becomes a problem, or in other words "the conversion of difficulties into problems" (Stone, 1989), is a complex process in which ideas and cognitive frames play a crucial role. Early studies on agenda setting have insisted on this central place of ideas in transforming difficulties into problems that are put on the agenda. Empirical examples abound in this aspect: why do tobacco or alcohol consumptions become a problem at one point in time, although alcohol and tobacco consumption is a centuries-old practice? Other problems such as food safety, the fight against cancer, housing policies, or the fight against terrorism are regularly put on the agenda. Some of these issues are linked to immediate events, such as terrorist attacks; others, however, are constantly part of the social and political system in which we live. Why then do they become a problem that political actors perceive to be necessary to address? In order to explain this process, it is possible to concentrate on the characteristics of actors participating in the agenda setting process -public or private -or the nature of the difficulties themselves -whether they are serious or mild, new or recurring, shortterm or long-term (Stone, 1989). Constructivist approaches, however, argue that it is only when we concentrate on the framing of the deliberate use of language and thus the framing of information available as a way of getting an issue on the political agenda -or, on the contrary, keeping it off -that we best understand why some issues make it on the agenda while others don't.The chapter is structured as follows. In the next section, the chapter aims to analyse the intimate, but very often implicit, relationship between constructivism and agenda setting by presenting the major claims and developments of constructivism with regard to the agenda setting process in policy studies. The subsequent section will outline the main controversies and show how constructivism has tried to answer the limitations of other approaches in the analysis of the agenda setting process. The final section will develop a series of issues that might be addressed in possible research agendas anticipating future developments.