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In many states the traditional distinctions between the culpability of accomplices and principals to a crime have been replaced by statute—including the felony murder rule that may make an accomplice guilty of first degree or capital murder if he was the lookout or getaway driver for a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 Connecticut, the law does not distinguish sharply between principals and accomplices; both are treated as equally culpable under the state's criminal statutes. According to Connecticut General Statutes, a person is considered an accomplice if they, with the intent to promote or assist the commission of a crime, aid, agree to aid, or attempt to aid another person in planning or committing the crime. This includes situations where the person acts as a lookout or getaway driver, as in the bank robbery example provided. Furthermore, under Connecticut's felony murder rule, an accomplice can be charged with murder if a death occurs during the commission of a felony such as robbery, even if the accomplice's role was limited to assistance rather than directly causing the death. This means that an accomplice to a bank robbery that results in a death could potentially face first-degree murder charges, reflecting the seriousness with which Connecticut law treats complicity in criminal acts.