Objective: We sought to (1) identify the outcome measures currently used across stroke arm rehabilitation randomized trials, (2) identify and compare outcomes important to stroke survivors, carers and clinicians and (3) describe where existing research outcome measures capture outcomes that matter the most to stroke survivors, carers and clinicians and where there may be discrepancies. Methods: First, we systematically identified and extracted data on outcome measures used in trials within a Cochrane overview of arm rehabilitation interventions. Second, we conducted 16 focus groups with stroke survivors, carers and clinicians using nominal group technique, supplemented with eight semi-structured interviews, to identify these stakeholders’ most important outcomes following post-stroke arm impairment. Finally, we described the constructs of each outcome measure and indicated where stakeholders’ important outcomes were captured by each measure. Results: We extracted 144 outcome measures from 243 post-stroke arm rehabilitation trials. The Fugl-Meyer Assessment Upper Extremity section (used in 79/243 trials; 33%), Action Research Arm Test (56/243; 23%), and modified Ashworth Scale (53/243; 22%) were most frequently used. Stroke survivors ( n = 43), carers ( n = 10) and clinicians ( n = 58) identified 66 unique, important outcomes related to arm impairment following stroke. Between one and three outcomes considered important by the stakeholders were captured by the three most commonly used assessments in research. Conclusion: Post-stroke arm rehabilitation research would benefit from a reduction in the number of outcome measures currently used, and better alignment between what is measured and what is important to stroke survivors, carers and clinicians.