In a control system for a compression-ignition engine whose operation is switchable between a compression-ignition operation in which an air-fuel mixture supplied to a combustion chamber auto-ignites to burn owing to compression and a spark-ignition operation in which the air-fuel mixture is ignited to burn by a spark of a spark plug, it is determined whether a predetermined permissible condition to permit switching from the spark-ignition to the compression-ignition operation is satisfied, and switching from the spark-ignition operation to the compression-ignition operation is permitted when the predetermined permissible condition is satisfied, thereby enabling to expand the compression-ignition operation utilization region so long as permissible in light of the engine operating condition.