The Capulidae, the cap snails or cap shells, are a taxonomic family of limpet-like sea snails, marine gastropod molluscs. Capulidae is the only family in the superfamily Capuloidea. According to taxonomy of the Gastropoda by Bouchet & Rocroi (2005) the family Capulidae has no subfamilies. Capulidae is assigned to the paraphyletic order Littorinimorpha, but is more closely related to neogastropods than some other littorinimorphs as it is a member of the clade Latrogastropoda.

The name Trichotropidae was previously used for this family, but this name is invalid, as it is a junior synonym.

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