Two prevalent explanations are that rising crime rates led to public demand for harsher policies and that politicians used crime policy to intensify public fears and win electoral favor. Both explanations have merit, but both are too simple. Instead, the analysis suggests that the rise in incarceration is the result of independent but interactive factors. The cause are is probably some combination of: (1) crime policy's broad appeal in an era of fractionated politics; (2) the unintended consequences of the war on drugs; and (3) the justice system's increased reflexivity that, with improved accountability and efficiency, becomes a major source of demand for its penal services. The incarceration rate can be expected to continue to rise for some time, even if the crime rate continues to decline. The political dynamics that have made crime control such a good platform for politicians reflect long-term changes in the political culture. It is less clear whether some of the brakes that once constrained cycles of governing through crime may begin to be felt. These brakes include popular sympathy for some lawbreakers, resistance from prison managers to increasing the population, and the potential demand of voters for other kinds of public goods such as education. Figures, footnotes, and 155 references (Author abstract modified)