A strut channel clamp includes a block that can be positioned anywhere along the length of the strut channel. In embodiments, the stop can be repositioned to any of a plurality of locations along the channel. In certain embodiments, the stop and block can be placed on different surfaces of the strut channel. In some embodiments, a threaded shaft engaged with the block imparts force against the stop, and in some of these embodiments the shaft can be disengaged quickly from the block and repositioned longitudinally without rotation thereof. In various embodiments, the stop and/or block are constructed partly or entirely from common, off-the-shelf strut channel accessories. In embodiments, the block is rotatable.