A plastic blow molding system (20) and a method for blow molding utilize an in-mold labeler (24) and a method for in-mold labeling a rotary plastic blow molding machine (22) includes a dispensing assembly (38) having a dispensing wheel (42) that is rotatably mounted on a base (40) and supports a plurality of dispensing head assemblies (46) each of which includes a support (48) and a dispensing head (50). An actuator (56) including first and second cam mechanisms (58, 64) moves the support (48) of each dispensing head assembly (46) along the rotary path of movement of an adjacent open mold (30) of the blow molding machine and angularly positions the support in alignment with a moving mold parting plane of the adjacent open mold in a manner that permits high speed operation of the in-mold labeling. Label transfer apparatus (160) provides high speed labeling of the dispensing assembly.