Recent studies have argued that political parties are increasingly orienting their actions at the institutional level, namely through the use of state resources and office-seeking strategies, disengaging from civil society and their social constituencies. The possibility that parties could strategically seek alternative channels of influence and support by attempting to foster grassroots mobilization or forge new links with organized civil society has been largely overlooked. Since the end of the Cold War the parties of the radical left had to address considerable strategic, organizational and ideological challenges. These incentives have led to a renewal of their engagement with civil society, leading to organizational adaptation and programmatic change. This strategy has been crucial for the survival and success of South European radical left parties, especially after the emergence of the 2008-2012 economic and financial crisis and the widespread social mobilization that has spread over the region. Drawing on the concept of “party linkage” elaborated by Kay Lawson, this paper analyzes the type of relationship that radical left parties establish with civil society. In particular, we will focus on two dimensions of linkages, namely participatory, on the one hand, and environmental, on the other. By examining the cases of South European radical left parties (Cyprus, Greece, Italy, Portugal and Spain), we will be able to assess the main characteristics of linkages to organized civil society (trade unions, associations, etc.), how this relationship varies across countries and party type, as well as why they decided to foster party linkages. Using data collected through elite interviews and party documents, this paper contributes not only to the analysis of the transformation of the radical left party family but also to the debate of party change in contemporary democracies.