This chapter describes the development of radical left activism in Scandinavia in the post-war period, with a particular focus on the last four decades. During this period, the main tendency in radical left activism shifted from party-based Marxism-Leninism to network-based, direct-action activism based on libertarian socialist ideals. Combining secondary literature with original quantitative and qualitative data on the radical left-libertarian movements (RLLM) in Sweden and Denmark, this chapter shows how RLLM activism emerged, expanded, and ultimately declined between the early 1980s and late 2010s. While there are key differences between the countries in terms of timing and issue foci, the chapter emphasizes the similarities between the countries. Tracing the movements’ development through sequential phases, the chapter shows them shifting from direct-action networks that engaged in a variety of political issue—anti-fascism, anti-imperialism, feminism, animal rights, etc.—to more “conventional” networks of organizations and initiatives through which activists intervened in local politics and neighborhood and workplace conflicts. The same period also saw the RLLM become less disruptive and violent, in favor of tactical pragmatism and conventional forms of protest. The chapter explains these changes as a combination of four main processes: (1) movement-internal developments, (2) changes in the countercultural milieus surrounding the movement, (3) the political institutionalization of the movement’s main counterpart, the far right, and (4) new patterns of protest policing and state repression.