Occlusal adjustment is a misunderstood and underutilized procedure that is often indicated in the management of occlusion-related disorders. To clarify the confusion extant about occlusal adjustment and to encourage its use, when appropriate, this paper examines optimal, normal and abnormal occlusions, classifies abnormal occlusions according to morphological and functional characteristics and treatment needs, and presents a rationale for occlusal adjustment based on these concepts. Differences between occlusal adjustment, occlusal equilibration and selective grinding are discussed, occlusal interferences are defined and described and the indications and contraindications for occlusal adjustment are presented.