Velopharyngeal dysfunction (VPD) is present in up to 40% of patients following cleft palate repair. Children with VPD display hypernasal speech, nasal air emission and are at a high risk for developing articulation disorders. The overall result is decreased intelligibility and acceptability of speech, as well as significant functional and social impairments. Although there are several surgical approaches for the management of children with VPD, standard treatment protocols have not been well defined. There is a need for a core outcome set (COS) to reduce outcome reporting bias and heterogeneity across studies of VPD. The COS-VPD Initiative is an international effort to establish a COS for the reporting of studies of the management of VPD. The study has been developed according to the Core Outcome Set-STAandards for Development standards for the design of a COS study and will be carried out according to the guidance of the Core Outcome Measures in Effectiveness Trials (COMET) initiative. A long list of clinical and patient-reported outcomes will be identified from a systematic review of the literature. A two-stage Delphi consensus process will be used to refine this list into a COS. An international panel of key stakeholders including patients, parents and multidisciplinary clinical and academic experts will be invited to participate in this process. Consensus criteria will be specified a priori and the steering group will ratify the final COS. The study has ethical approval through Children's Health Ireland at Crumlin Research and Ethics Committee, Ref: GEN/683/18. The study is registered with the COMET Initiative (http://www.cometinitiative.org/studies/details/1146?result=true). The COS will be disseminated by publication in the peer-reviewed literature, presentation at international research meetings and distribution to patient-representative organisations. This will facilitate the application of the COS in future studies of the management of VPD. © Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.