Background: Two classifications of retinoschisis were published in the 1960s. A marked expansion of our knowledge of the diseases that give rise to retinoschisis indicates the need for an updated classification. Methods: The new classification is based on the authors' clinical experience, an extensive review of the literature, and a survey of 20 vitreoretinal specialists. Results: There are three types of retinoschisis: degenerative, hereditary, and secondary. Degenerative retinoschisis is very common and has been published extensively. In addition to the well known X-linked hereditary retinoschisis, there are less common pedigrees with autosomal recessive or autosomal dominant patterns. There are at least 18 ocular diseases that may show varying degrees of secondary retinoschisis. Conclusion: The many types of retinoschisis are divided into these major categories. The multiplicity of types is emphasized by the plural form of the term: “the retinoschises.”