The invention provides anchoring devices and methods for coupling an object, such as a suture or soft tissue, to bone. In one aspect of the invention, a bone anchor is placed into compression fit with a predrilled bone hole by pulling an insertion stem at least partially into an anchoring element. In its non-expanded state, the anchoring element is slidably mounted on the proximal end of the insertion stem. The anchoring element has an axial channel at least a portion of which has an inner diameter (or cross-section) smaller than an outer diameter (or cross-section) of at least one portion of the insertion stem. As that larger portion of the insertion stem is pulled through the channel, it causes the walls of the anchoring element to expand outwardly and, thereby, to engage the bone hole walls in a pressure or compression fit. In another aspect of the invention, the larger portion of the insertion stem is a separate component, referred to as an "expander element," that is slidably mounted on the insertion stem distal to the anchoring element. As the insertion stem moves proximally, the expander element is pulled through the channel, causing the walls of the anchoring element to expand into the bone hole walls. A flange, such as a reverse taper, at the distal end of the expander element prevents it from being drawn too far through the anchoring element.