Composite resins have been improved dramatically over the last few years. Some of the newest formulations are nearly as wear resistant as amalgam. Under the appropriate conditions, they may be used to restore Class I and Class II cavity preparations. Their use, however, must be in accordance with the conditions described in this paper. The following conditions should be followed: The selection of a posterior composite resin should be based on well-documented clinical data, not physical and mechanical properties. Complete moisture control is essential for the successful restoration of posterior teeth with composite resin. Always use a glass ionomer as a liner. The material should cover all the dentin. Cavity preparations should be minimal in dimension. Avoid unnecessary removal of tooth structure. Do not bevel the occlusal cavosurface margin. Insert the composite in increments. Minimize introduction of trauma during the finishing procedure. Use a surface penetrating sealant to reduce wear rate and to enhance margin integrity. Evaluate carefully the clinical performance of the restored tooth at least once a year. Discuss possible limitations of posterior composite resins as compared with amalgam restorations.