This study characterizes the corporate leniency policy that minimizes the frequency with which collusion occurs. Though it can be optimal to provide only partial leniency, plausible sufficient conditions are provided whereby the antitrust authority should waive all penalties for the first firm to come forward. It is also shown that restrictions should be placed on when amnesty is awarded, though it can be optimal to award amnesty even when the antitrust authority is very likely to win the case without insider testimony.