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In many states the traditional distinctions between the culpability of accomplices and principals to a crime have been replaced by statute—including the felony murder rule that may make an accomplice guilty of first degree or capital murder if he was the lookout or getaway driver for a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 Delaware, the concept of an accomplice is covered under the state's criminal code. An accomplice is someone who assists in the commission of a crime with the intent to promote or facilitate the commission of that crime. This can include acts before, during, or after the crime that are intended to aid in its success. Delaware law does not strictly differentiate between principals and accomplices; instead, it holds accomplices liable to the same degree as the person who actually commits the criminal act. This means that if an individual acts as a lookout or getaway driver during a bank robbery, they can be charged with the same offenses as the person who physically carries out the robbery. Furthermore, under Delaware's felony murder rule, an accomplice can be found guilty of first-degree murder if a death occurs during the commission of certain felonies, such as robbery, even if the accomplice's role did not directly involve harming the victim. This reflects the state's approach to holding all participants in a crime responsible for the outcomes of that criminal activity.