ABSTRACT Maxillary transverse deficiency usually requires expansion of the palate by a combination of orthopedic and orthodontic tooth movement. Expansion of the maxilla and the maxillary dentition can be achieved by various ways. The skeletal and dental pattern influences the choice of expansion appliance and the type of expansion chosen will significantly facilitate the overall goals of treatment. Rapid maxillary expansion entails the use of heavy and continuous forces that are transmitted to the maxilla over a short period of time, which inadvertently produces an immediate and an effective increase of the maxilla in the transverse dimension. This expansion can be either produced symmetrically such that the arch expands uniformly, or differentially, where one section of the arch expands more than the other. This article aims at throwing light on differential rapid maxillary expansion, the appliances that produces it and its advantages over the other rapid maxillary expanders. KEYWORDS: Maxillary transverse deficiency, rapid maxillary expansion, differential expansion, expander with differential opening