Abstract: A laterally adjustable harvester head assembly for a cotton harvesting machine has a width greater than the remainder of the machine, and is selectively linearly movable from a normally centered position at the front of the machine to a laterally offset position. The normally centered position is essentially laterally symmetrical relative to the remainder of the machine and is the position of choice for the head assembly during cotton harvesting operations, with the ends of the harvester head extending past the sides of the wheeled portion of the machine in order to harvest a greater number of rows simultaneously. The laterally offset position displaces the head assembly laterally from its centered position, to essentially align one end of the head assembly with the corresponding side of the harvester machine.