Multispecies Justice (MSJ) is a theory and practice seeking to correct the defects making dominant theories of justice incapable of responding to current and emerging planetary disruptions and extinctions. Multispecies Justice starts with the assumption that justice is not limited to humans but includes all Earth others, and the relationships that enable their functioning and flourishing. This Element describes and imagines a set of institutions, across all scales and in different spheres, that respect, revere, and care for the relationships that make life on Earth possible and allow all natural entities, humans included, to flourish. It draws attention to the prefigurative work happening within societies otherwise dominated by institutions characterised by Multispecies Injustice, demonstrating historical and ongoing practices of MSJ in different contexts. It then sketches speculative possibilities that expand on existing institutional reforms and are more fundamentally transformational. This title is also available as Open Access on Cambridge Core.