Are we able to do everything we ought to do? According to the important but controversial Ought Implies Can principle, the answer is yes. In this book Alex King sheds some much-needed light on this principle. She argues that it is flawed because we are obligated to perform some actions that we cannot perform, and goes on to present a suggested theory for anyone who would deny the principle. She examines the traditional motivations for Ought Implies Can, and finds that they to a large degree do not support it. Using examples like gay rights, addiction, and disability, she argues that we can preserve many of the motivations that led us to the principle by thinking more about what we, as individuals or institutions, can fairly demand of ourselves and each other.