Whether it's people incarcerated in prisons, or animals confined in zoos, aquariums, laboratories, farms, and in our own homes, millions of upon millions of sentient creatures live in captivity. To be held captive, some might say, is to be denied basic rights of autonomy. But physical captivity, others might say, can have significant social benefits. So under what conditions could it be morally justified to hold a creature in captivity? Should we think of humans and animals differently? And in a civil society, is captivity a necessary harm, or should we work towards eradicating it?