Gouraud shading and Phong shading are widely used interpolation methods to render a polygon mesh of a curved surface. When an illumination equation has a specular reflection term Phong shading produces more realistic results than Gouraud shading. The specular highlights produced by Phong shading give visual information about surface geometry and properties. But it is not implemented in most graphics workstations and software renderers due to its computational expense. This paper introduces an adaptive shading method that produces Phong-shaded quality images for a small increase in rendering time using Gouraud shading systems. Higher quality images can be obtained from existing graphics hardware or software through a simple modification of the application or library.