A plugging device, well system and method. In one example, a wrap, band or other type of binding is utilized to secure together multiple fibers, tubes, filaments, films, fabrics or lines of the plugging device. In another example, fibers, tubes, filaments, films, fabrics or lines are fused, adhered or bonded to an outer surface of a body of the plugging device. In other examples, a material of the plugging device may become more rigid or swell in a well. A plugging device may comprise a body loosely enclosed in a bag, wrapper or other enclosure.