PREHEAT grill to medium-high heat. Place 1 chicken breast half in center of 18x12-inch sheet of heavy-duty foil. Spoon barbecue sauce over chicken; top with vegetables.
BRING up foil sides. Double fold top and ends to seal packet, leaving room for heat circulation inside. Repeat to make 4 packets.
PLACE packets on grate of grill; cover with lid. Grill 12 to 15 min. or until chicken is cooked through (170°F) and vegetables are tender.