Abstract: A plaster crown molding tile system has an upright body portion providing a front decorative surface and a rear wall-engaging surface. Integral with the body portion, a topper portion extends angularly upwardly. A first tile provides a laterally extensive linear portion, the rear wall-engaging surface of the linear portion configured for surface-to-surface contact with a generally flat wall. The linear portion terminates at one end with an integral corner-turning portion which is small in lateral proportion to the linear portion. The rear wall-engaging surface of the corner-turning portion is oriented for contact with a second generally flat wall usually set at a right angle to the first wall. The corner-turning portion terminates laterally with a non-mitered first edge, laying in a plane generally perpendicular to the second generally flat wall wherein the first edge abuts a linear tile with a second edge conforming to the first edge for forming a uniformly tight butt seam.