Abstract: A rotatable fastener for attaching trim strips to vehicle window assemblies and other vehicular trim supports includes a pair of trim engaging flanges at one end of a central shaft and a retaining head at the other end. The flanges are beveled to engage the edges of a trim strip slot upon one-quarter turn rotation after insertion through an aperture in the window assembly or trim support. The retaining head includes recesses for engaging projections on the window assembly or trim support after rotation to resist removal. The flanges are preferably offset and the aperture shaped to receive the offset flanges and central shaft to resist fastener movement in the aperture and slot. Alternately, the fastener may include a planar head while the flanges may each include a flexible portion and slot for reducing the width of the flanges upon insertion.