Comprehensive, efficient assessment of work-related activity limitations is imperative to government disability programs and clinicians working with patients experiencing work limitations. This article describes the development and initial validation of a newly developed instrument: the Work Disability Functional Assessment Battery (WD-FAB). The WD-FAB characterises physical and mental function across 8 key dimensions related to work: Basic Mobility; Upper Body Function; Fine Motor Function; Community Mobility; Mood & Emotions; Resilience & Sociability; Self-Regulation; and Cognition & Communication. The WD-FAB draws upon a pool of over 300 items to generate scores for all 8 scales in under 15 minutes. WD-FAB scores allow direct comparisons between individuals with self-reported activity limitations and sex- and age-matched adults. Future research with the WD-FAB in both the US and Europe has potential implications for enhancing disability assessment methodologies within the context of disability determination and insurance medicine systems.