A concealed slide-on trim attachment method reduces the work effort and materials involved to refinish walls, ceilings, or anywhere trim is attached on a building using the conventional nailing method. When removing the existing trim, this invention eliminates the damage to the trim, walls, and ceilings, along with the issues previously associated with the current fastening process. With this invention, refinishing or renovation of the trim, walls, ceilings or any other associated building components can be completed without damage to surrounding surfaces or the existing trim, making the trim reusable. This is a simple way to attach and detach the trim when compared to the current nailing method or use of other fasteners. During initial construction, this invention may also reduce time and man-hours required for installation.