This paper aims at examining the main characteristics of the populations of interest groups in Spain and in Portugal in its most recent form. The idea is to identify the number of relevant interest groups involved in national politics in each of the two countries, as well as to describe the similarities and differences in the four following topics: representation, fragmentation, competition, and associational typology. We will analyze original data from interest groups that are engaged at present in advisory committees, the various lobbying registers, and parliamentary appearances in both countries. Our main theoretical focus relates to the population ecology and how the number and diversity of groups shapes the network of interest groups. By examining Spain and Portugal, this paper also links to the literature on democratic consolidation, since these two countries share past authoritarian experiences that raised doubts regarding the consolidation of an active and plural civil society. In this sense, we explore likewise whether there is a unique Southern-European type of interest groups population or not, considering the many institutional similarities that exist among this two South European countries.
