Introduced by Fernand Braudel in 1958 with the aim of addressing historically long-lasting patterns of social relationships and cultural conceptions, the concept of “longue durée” has since then been methodologically refined. Today and following Reinhard Koselleck’s rationale about the intermingling of time layers (“Zeitschichten”), social science methodology heuristically distinguishes three of these layers. While short-term social processes (“temps court”) unfold in moments, hours, or days, and medium-term processes cover the memory of the living, long-term processes (longue durée) – which are the focus of this session – unfold over decades or centuries and thus go beyond not only the memory of the living but possibly attain temporal moments prior to the Anthropocene age. Since its inception, the concept of longue durée has underpinned historical and historical-sociological research on how past economic, political and ecological processes such as colonialism, nationalization, industrialization, urbanization have been influencing societies even today. This session will tackle the concept’s methodological value, gains and challenges. They remain relatively underexplored, particularly against the empirical backdrop of the (current 21st century) world immersed in apparently irreversible historical changes – for example, if we take into account the onset of the Covid-19 pandemic amidst the socially and environmentally devastating effects of climate change, of the socially unequal global spread of digitalization and the pervasiveness of hybrid wars. The session is receptive to papers that address the value, gains and challenges implicit in the use of the concept of the longue durée in the social sciences in the 21st century by tackling questions such as: Which data and methods can be used for analyzing which types of issues in the longue durée? How to sample and generalize when analyzing long-term social processes with the aid of the longue durée, especially if analyses aim to be delinked and decentered? How can we methodologically assess specific temporal patterns of social change, such as trajectories, cycles or turning points which mark irreversible historical ruptures? How can we apprehend the overall duration, the timing of key events, the pace of processual change and rhythm, and/or how short-term, medium-term and long-term processes interact with one another? How can we assess causal effects when long-term social processes are involved? For example, how do these processes influence and/or explain how societies have been handling e.g. the Covid-19 pandemic, climate change or digitalization, current geopolitics, wars or social inequality, and how can we methodologically grasp these types of relationships? The session equally welcomes papers that address these issues either from a theoretical-methodological perspective or use specific empirical examples.