Abstract: An archery bowstring accessory includes a unitary longitudinally elongated body having a head end portion, a tail end portion, and an intermediate section extending therebetween. The intermediate section is configured to extend longitudinally along a bowstring in an orientation which configures the head end portion more proximate a limb end of a bow which receives said bowstring than is the tail end portion. As so received, the head end portion constitutes a speed increasing mass effective to impart increased arrow speed in an arrow shot by said bowstring of said bow than would otherwise occur in an identical arrow shot in the absence of the speed increasing mass. As so received, the tail end portion constitutes a vibration dampening mass effective to impart reduced bowstring vibration in said arrow shot than would otherwise occur in said identical arrow shot in the absence of said vibration dampening mass. Methods are disclosed.