Animal Liberation is a 1975 book by Australian philosopher Peter Singer. The book is widely considered within the animal liberation movement to be the founding philosophical statement of its ideas. Singer himself rejected the use of the theoretical framework of rights when it comes to human and nonhuman animals: he argued that the interests of animals should be considered because of their ability to feel suffering and that the idea of rights was not necessary in order to consider them. He introduced and popularized the term "speciesism" in the book, which was originally coined by Richard D. Ryder, to describe the exploitative treatment of animals.

The central argument of the book is an expansion of the utilitarian idea that 'the greatest good' is the only measure of good or ethical behaviour. Singer argues that there is no reason not to apply this to other animals.

Although Singer rejects rights as a moral ideal independent from his utilitarianism based on interests, he accepts rights as derived from utilitarian principles, particularly the principle of minimising suffering. Singer allows that animal rights are not the same as human rights, writing in Animal Liberation that "there are obviously important differences between human and other animals, and these differences must give rise to some differences in the rights that each have."

Animal liberation may refer to:

Peter Albert David Singer (born 6 July 1946) is an Australian philosopher who is the Ira W. DeCamp Professor of Bioethics at Princeton University and Laureate Professor at the Centre for Applied Philosophy and Public Ethics at the University of Melbourne. He specialises in applied ethics and approaches ethical issues from a secular, preference utilitarian perspective.

He has served, on two occasions, as chair of philosophy at Monash University, where he founded its Centre for Human Bioethics. In 1996, he unsuccessfully stood as a Greens candidate for the Australian Senate. In 2004, he was recognised as the Australian Humanist of the Year by the Council of Australian Humanist Societies. He has been voted one of Australia's ten most influential public intellectuals. Singer serves on the Advisory Board of Incentives for Global Health, the NGO formed to develop the Health Impact Fund proposal.

Outside academic circles, Singer is best known for his book Animal Liberation, widely regarded as the touchstone of the animal liberation movement. Not all members of the animal liberation movement share this view, and Singer himself has said the media overstates his status. His views on that and other issues in bioethics have attracted attention and a degree of controversy.