Abstract: An anti two-blocking device for preventing a lower load block (46) on a crane (10) from coming in contact with an upper load block (44) affixed adjacent a boom point (40). The device comprises a cable follower (60) through which the crane's cable (26) is threaded, situated between the upper load block (44) and the lower load block (46). When the lower load block (46) is within a predetermined distance of the upper load block (44), the lower load block (46) reaches the cable follower (60) and exerts an upwards force which causes the cable follower (60) to activate an actuator (70) for a switch (72). The switch (72) deactivates all activity on the crane (10) which could cause the lower load block (46) to come in contact with upper load block (44). This activity includes lowering the boom (30), reeling in the cable (26) and extending the telescoping sections of the boom (32 and 33).