A method of joining parts together with a self-piercing rivet that is inserted through a part and partially through a second part. The second part includes a fiber-filled layer and a resin matrix layer that together form a composite part. A self-piercing rivet extends into the second part, but does not penetrate completely through the matrix layer. An assembly, including a first part and a second part that includes a reinforced layer and a resin layer in which a fastener is inserted, but does not extend through the second layer. A composite part including a first layer of resin matrix reinforces the filler and a second layer of resin matrix that does not include a filler and is more than 3 microns thick.