Abstract: A device for practicing putting strokes includes flexible side walls which enclosingly define the putter's swing area and the intended travel path of a struck golf ball so that a faulty putting swing may be detected when the struck ball deviates from the intended path. The side walls extend between a spaced pair of vertical support surfaces and are adjustably demountably interlaced in slots therein so that the spacing between the supports and the spacing between the side walls may be altered. The flexible side walls may be formed by a single elongated flexible strap. Weighted stabilizer blocks may be attached to the outwardly facing surfaces of the side walls. The practice device may also be configured to provide for anchoring of the supports to suitable fixed objects.