A stent delivery system can include a core wire and a self-expanding member disposed along the core wire. The self-expanding member can be used to facilitate expansion of a stent or other implantable device within the vasculature of a patient. The self-expanding member can include first and second end portions that are each axially slidable along the core wire and be able to expand from a collapsed configuration to an expanded configuration upon axial convergence of the first and second end portions.