Noninstitutional participation is often assumed to be conventionalized, yet its forms differ by mobilisation context. This study distinguishes insiders and outsiders based on their embeddedness in the dominant cleavage’s organisational landscape. Using an original survey from Germany during the Covid-19 crisis, the analysis shows insiders and outsiders engage equally in noninstitutional protest but focus on different issues: insiders on climate and anti-racism, outsiders on economic assistance and civil liberties. Dynamic models reveal volatile issue preferences underpinning participation, pointing to a differentiated protest arena.