Purpose: Although hearing health care clinicians provide training on hearing aid handling and management as part of the rehabilitation program, clinical studies suggest that the level of management skill demonstrated by hearing aid owners is low. In the absence of a comprehensive clinical survey to identify these shortfalls in clinical training, the objective of this study was to develop and report the psychometric properties of the Hearing Aid Skills and Knowledge Inventory (HASKI: a self-administered version and a clinician-administered version). The HASKI evaluates the knowledge and skills required for hearing aid management. A secondary aim was to report the prevalence of hearing aid management difficulties in an Australian population. Method: The development of the HASKI and the investigation of its psychometric properties in a prospective convenience cohort of 518 adult hearing aid owners, ranging in age from 18 to 97 years (M = 71 years, SD = 14), 60% male, 38% female, and 2% undisclosed, recruited from 7 hearing clinics across Australia, were used. Results: The HASKI (both the self-administered and clinician administered) demonstrated high internal consistency, interdimensional relationships, construct validity, test–retest reliability, interobserver reliability, and criterion validity. A range of aptitudes were observed from low to full competency, with 99% of participants indicating difficulty with at least 1 item on the survey. Conclusions: The Hearing Aid Skills and Knowledge Inventories are valid and reliable measures of hearing aid handling and management skills with good potential for use in clinical settings. Hearing aid management is an area of difficulty for the majority of hearing aid owners, indicating the need for clinicians to improve the efficacy of hearing aid management training delivered.