A mortise and tenon jig includes a base plate, a router support plate attached to an upper surface of the base plate such that the router support plate includes an opening, and a guide attached to the router support plate. The guide may include a first end and a second end. The first end includes a mortise guide surface, and the second end includes a tenon guide surface. The mortise and tenon jig also includes a first configuration where the mortise guide surface is aligned with the opening and a second configuration where the tenon guide surface is aligned with the opening.