Objectives: Severe to profound hearing loss is associated with communication, social, and behavioral difficulties that have been linked to worse health-related quality of life (HRQoL) compared to individuals with normal hearing. HRQoL has been identified as an important health outcome that measures functional ability, particularly for chronic conditions and disabilities. The current study developed the QoL-cochlear implant (CI) for early childhood and adolescents using the recommended Food and Drug Administration and European Medicines Agency guidelines on patient-reported outcomes., Design: Three phases of instrument development were conducted for both the early childhood (0 to 5 years old; parent proxy) and adolescent/young adult (13 to 22 years old) versions of the QoL-CI. Phase 1 included the development of our conceptual framework, which informed the discussion guides for stakeholder focus groups (e.g., audiologists, physicians, and therapists) at CI clinics in Miami and Philadelphia (n = 39). Open-ended interviews with parents (N = 18 for early childhood; N = 6 for adolescent/young adult version) and adolescents/young adults using CIs (n = 17) were then completed at both sites during phase 2. All interviews were transcribed and coded to identify common themes, which were then used to draft items for the QoL-CI. Both versions of the QoL-CI were developed using Qualtrics to allow for quick, easy electronic administration of the instruments on a tablet device. Last, phase 3 included cognitive testing in a new sample (N = 19 early childhood, N = 19 adolescent) to ensure that the draft instruments were clear, comprehensive, and easy to use., Results: Participant responses obtained via the open-ended interviews yielded an early childhood and adolescent version of the QoL-CI that was reportedly easy to complete and comprehensive. The final QoL-CI Early Childhood instrument yielded 35 questions across eight functional domains (environmental sounds, communication, social functioning, behavior, CI device management and routines, school, CI benefits, and early intervention). Similarly, the final QoL-CI adolescent/young adult version consisted of 46 items across eight domains (noisy environments, communication, CI usage and management, advocacy, social functioning, emotional functioning, acceptance, and independence)., Conclusions: The QoL-CI is a condition-specific QoL instrument that can be used for children ages birth through 22 years. These instruments capture the "whole" child by not only focusing on communication and auditory skills but also academic, social and emotional functioning. Once validated, these CI-specific measures will enable providers to track long-term outcomes and evaluate the efficacy of new interventions to improve overall CI use and QoL for pediatric and young adult users., Competing Interests: Dr. Cejas is on the AG Bell Board of Directors and is a consultant for Advanced Bionics. Dr. Sanchez is a consultant for Advanced Bionics and is on the MED-EL bilingual task force. The other authors have no conflicts of interest to disclose., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)