Abstract: The invention provides a mower attachment for a lawn or garden tractor carried on the tractor for movement between transport and operating positions. An articulated boom structure is guidably supported for up and down pivotal movement to provide for a predetermined substantially horizontal low path of movement for a mower unit at the free end of the boom structure, and for utilization of the weight of the mower unit in extending the boom structure during pivotal movement thereof. Extension of the boom structure is yieldably resisted by a spring unit which also functions to provide a floating action of the mower unit in following the ground contour in a mowing operation.