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In many states the traditional distinctions between the culpability of accomplices and principals to a crime have been replaced by statute—including the felony murder rule that may make an accomplice guilty of first degree or capital murder if he was the lookout or getaway driver for a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 Louisiana, the concept of an accomplice is covered under the state's criminal laws. An accomplice in Louisiana is someone who aids, abets, or assists another person in the commission or attempted commission of a crime, with the intent to promote or facilitate the commission of the crime. This can include acts before, during, or after the crime that are intended to contribute to the crime's success. Louisiana law does not strictly differentiate between principals and accomplices; rather, all parties involved in the commission of a felony can be charged and prosecuted as principals. This means that a lookout or getaway driver can be charged with the same offense as the person who actually commits the crime. Furthermore, under Louisiana's felony murder rule, if a death occurs during the commission of certain felonies, such as a bank robbery, all participants can be charged with first degree murder, regardless of their level of direct involvement in the act that caused the death.