The aim of this study was to use the Delphi method to develop and validate an ontology for one class of assistive technology (AT), namely physically controllable pointing devices. A three-round, structured process consisting of responses to a series of questionnaires was used to identify items and categories of importance to pointing device prescription from six occupational therapists with AT expertise. The intraclass correlation coefficient (ICC) was used to assess the interrater reliability of items included in categories related to the pointing devices and to the user profile by the six experts during each Delphi round. During the first round, the ICC ranged from 0.19 to 0.97; this improved to ICCs ranging from 0.72 to 1.0 during the second round. A full consensus was reached by the experts during the final round which included 218 items, divided into five categories, for the pointing device list, and 168 items, divided into six categories, for the user profile list. This ontology is expected to help achieve a more systematic regulation of the AT field, leading to greater standardization and increased knowledge sharing, which may help novice clinicians to achieve a level of competence in matching AT to a person with special needs.