The transition to lower-carbon sources of energy will inevitably produce and, in many cases, perpetuate pre-existing sets of winners and losers. The winners are those that will benefit from cleaner sources of energy, reduced emissions from the removal of fossil fuels, and the employment and innovation opportunities that accompany this transition. The losers are those that will bear the burdens, or lack access to the opportunities. Here we review the current state of understanding—based on a rapidly growing body of academic and policy literature—about the potential adverse consequences of the energy transition for specific communities and socio-economic groups on the frontlines of the transition. We review evidence about just transition policies and programmes, primarily from cases in the Global North, and draw conclusions about what insights are still needed to understand the justice and equity dimensions of the transition, and to ensure that no one is left behind.