A criminal accomplice is a person who knowingly, voluntarily, or intentionally assists another person in the commission of a crime—or under some circumstances, a person who fails to prevent another person from committing a crime. Unlike a person who aids and abets a crime by helping with the planning of the crime but is often not present at the scene of the crime—and unlike an accessory after the fact, who is not present at the scene of the crime but assists after the commission of the crime to help the perpetrator avoid arrest or punishment—an accomplice actively participates in the commission of the crime. For example, a person who acts as a lookout or getaway driver for a bank robbery is an accomplice.

In many states the traditional distinctions between the culpability of accomplices and principals to a crime have been replaced by statute—including the felony murder rule that may make an accomplice guilty of first degree or capital murder if he was the lookout or getaway driver for a bank robbery that resulted in a death.

In Wyoming, an individual who assists in the commission of a crime is considered an accomplice and can be charged with the same degree of offense as the principal offender. This includes those who aid, abet, counsel, encourage, or otherwise facilitate the commission of a crime, whether they are present at the crime scene or not. Wyoming law does not make a significant distinction between the principal and the accomplice; both can face the same legal consequences. Furthermore, under the felony murder rule in Wyoming, an accomplice can be charged with first-degree murder if a death occurs during the commission of a felony, such as a bank robbery, even if the accomplice's role was limited to being a lookout or getaway driver. This reflects the state's stance on holding all participants in a crime responsible for the outcomes of the criminal act.