The effects of the death penalty are widespread and difficult to determine specifically. One problem with talking about the effects of the death penalty is that they vary across cultures and countries and may be different in specific cases or for specific crimes. In general, it is believed that the death penalty can discourage crime but that in many cases it fails to play a role in whether a crime is committed. There are many other consequences of the death penalty, including the emotional impact on executioners, the effect on prison populations when executions actually occur, and the varied fallout on families of executed criminals. In order to determine the effects of the death penalty, one must research the question as specifically as possible.

When most people think of the effects of the death penalty, the question that is really being asked is whether crime is being reduced overall. This question can be answered only in regard to specific areas and only for specific time periods. One factor that is known to make the death penalty more effective as a crime deterrent is the rate of executions, with fast and frequent executions reducing crime. Unfortunately, executing many people has other ethical and social effects as well, which may not be worth a superficial reduction in crime.