Abstract: The device and method of the invention enables a single workman to drive a tongue and groove subflooring panel into mating connection with a prelaid subfloor panel without the use of a sledgehammer. The device fits over and receives and is secured to the usual driving plank as an operative part thereof. An elongate handle extends upwardly and backwardly at an acute angle to and from its lower end portion, which is fastened to the upper face of the plank centrally and transversely thereof so the workman standing on the panel facing forwardly with his legs spread apart longitudinally therealong uses his weight to flatten the panel while he forcefully pulls the device backwardly, so the driving plank, whose rearward longitudinal edge face abuts the grooved forward edge face of the subfloor panel to be driven, drives such subfloor panel into mated connection with a rearwardly positioned, prelaid, subfloor panel.