A system for attaching soft tissue to bone includes an anchor, a suture, and a tissue retainer. The anchor may have a threaded tip that engages the bone, and a suture retention portion with passageways arranged such that each of first and second anchor portions of the suture can be drawn through the passageways along only a single direction. The tissue retainer has passageways through which the suture can freely move in either direction. Thus, the anchor and the tissue retainer may be attached to bone and tissue, respectively, and the suture may be drawn to substantially irreversibly draw the bone and tissue together. In alternative embodiments, an anchor may receive only one portion of suture and/or one suture end may be affixed to the anchor. The anchor may alternatively permit free motion of the suture, while the tissue retainer permits passage of the suture along only one direction.