In this chapter, I explore the destabilising role of social mobilisation and cultural shifts, in creating ruptures and generating demands for alternative energy systems and in actually doing the work of transition and wider transformative change by building alternative pathways. I briefly trace early struggles over energy systems from the London smogs and creation of the UK Factories Act during the industrial revolution, through the long histories of indigenous forms of activism against extractivism, to contemporary battles for energy and climate justice, and resistance to new infrastructures, projects and policies that further embed rather than disrupt the fossil fuel economy. I point to how mobilisations have sought to challenge existing political economies and distributions of power, as well as to construct alternative ones. I explore the interrelationships between strategies then describe the rich ecology of resistance, including lobbying, litigation and direct action, pressuring all parts of systems of production, finance and governance, as well as seeding alternatives for incumbent actors to crush or ignore, co-opt or replicate and learn from, or even support and scale up.