Few issues bedevil criminology and criminal justice as much as free will versus determinism. It goes to the heart of the character of the people they deal with and how we should respond to them. People are held morally responsible for what they do only if we believe that they have the ability to make reasoned choices to act morally. Liberals tend to hold an external locus of control and are skeptical of free will, and conservatives tend to favor an internal locus of control and embrace free will. This liberal-conservative divide reveals itself in the theories they favor as the best explanations of criminal behavior. Liberals favor explanations external to criminals such as an unfair economic system or criminal justice bias; conservatives tend to favor internal explanations such as low self-control or lack of empathy. In terms of responding to criminal behavior, there have been calls to abandon the idea of punishment and abolish prisons. Liberals may tend to view this as humanitarian while conservatives will tend to view them as incredibly naïve. The greater tendency of liberals to hold an external locus of control and their skepticism about free will lead them to view people’s behavior as largely beyond their control, which accounts for their punishment abolitionist stance. The greater tendency of conservatives to believe in free will and an internal locus of control leads to a more punitive stance toward criminals. Many issues that divide liberals and conservatives in criminology-criminal justice may be traced to their beliefs about free will and determinism.