Today, human exceptionalism is the norm. Despite occasional nods to animal welfare, we prioritize humanity, often neglecting the welfare of a vast number of beings. As a result, we use hundreds of billions of vertebrates and trillions of invertebrates every year for a variety of purposes, often unnecessarily. We also plan to use animals, AI systems, and other nonhumans at even higher levels in the future. Yet as the dominant species, humanity has a responsibility to ask: Which nonhumans matter, how much do they matter, and what do we owe them in a world reshaped by human activity and technology? In The Moral Circle, philosopher Jeff Sebo challenges us to include all potentially significant beings in our moral community, with transformative implications for our lives and societies. This book explores provocative case studies such as lawsuits over captive elephants and debates over factory-farmed insects, and compels us to consider future ethical quandaries, such as whether to send microbes to new planets, and whether to create virtual worlds filled with digital minds. Taking an expansive view of human responsibility, Sebo argues that building a positive future requires the shedding of human exceptionalism and radically rethinking our place in the world.