This bankruptcy is devoted to the mechanisms of engagement and disengagement in collective movement as they may be currently conceived in social and political psychology Dynamics of collective movement are decomposed into dynamics of call for, deliver, and mobilisation. Dynamics of demand are approximately humans and their motives, dynamics of supply approximately businesses and their appeals, and dynamics of mobilisation approximately the convergence of demand and supply. thus far, the core enterprise of political psychology has been the call for aspect of protest. This bankruptcy describes five core standards affecting collective action participation: grievances, efficacy, identity, feelings, and embeddedness. As for the deliver facet of protest and mobilisation, psychosociological research strains (framing, the perceptions of the sociopolitical context, and the role of social media for dynamics of mobilisation and participation) are discussed. The bankruptcy closes with a discussion of new directions research technique has taken.