An agreement, between 2 or more parties, to commit an unlawful act.
"Agreement" requires meeting of the minds, specific intent, and an overt act in furtherance of the conspiracy.
"overt act" any little act is sufficient.
Liability: All co-conspirators are liable for all crimes committed in furtherance of the conspiracy so long as it was foreseeable. However, not responsible for crimes committed after withdrawal.
Unilateral MPC Approach: Doesn't require more than 1 person. Other guy can be an undercover cop.