The genera Asterodiscides A. M. Clark, Paulia Gray and Amphiaster Verrill are compared and assigned to a new family. The relationship between Paulia and Pauliella is discussed. Five new species and one new subspecies are described for the genus Asterodiscides with the holotype of the type-species, Asterodiscus elegans Gray, being fully described for the first time. Asterodiscus hiroi Hayashi is considered to be conspecific with A. helenotus (Fisher) and two juvenile specimens of the species are described. Examination of many juvenile specimens has allowed an assessment to be made of the relative constancy of form of the various structural elements used in determining specific limits within the family. A key is given to the genera and species of the family.