'Solidarity' has received considerable scholarly attention and is central in many social justice movements. It is striking, then, that solidarity's relevance, meaning and practical implications in the context of animal protection have not been systematically explored. This is particularly surprising given the recent so-called 'political turn' in animal ethics. Work in the political turn accepts claims about the moral status of animals and people's personal obligations towards them, but advances the field in at least two ways. First, thinkers emphasize that mutually beneficial human-animal relations cannot rely solely on personal transformation, but also require institutional transformation. Secondly, scholars claim that to meaningfully improve the lives of animals, we must not only change our political systems, but better understand various animals' own perspectives and political agency to feed into 'more-than-human politics'. But while much work in this political turn has been done on concepts like 'justice', 'agency', 'representation', etc., only very few animal scholars have talked about 'solidarity'. And those that have, have done so only in very specific contexts and frameworks. This lack of attention is also mirrored also within animal activism, where those few campaigners who have employed the term have done so only in a very loose way. This edited collection brings together the leading thinkers in the fields of animal ethics, politics, social philosophy, world religions, and the law to explore this lacuna and thus provide the first book length treatment of solidarity between the species.