Construction productivity is a key performance indicator in building construction projects because it directly affects project time, cost, quality, and resource efficiency. This study aims to identify and rank the main factors affecting construction productivity in the UAE building construction industry. Based on a review of Scopus-indexed literature, 38 productivity sub-factors were classified into six categories: labor/workforce, project-related, materials and equipment, construction site, management, and external factors. A structured questionnaire survey was distributed to professionals working in UAE building construction projects, and 30 valid responses were analyzed using the Relative Importance Index method. The results show that material and equipment maintenance/equipment breakdown, labor skill and experience/labor shortage, proper supervision, poor work site condition, and delay in payment are the most prominent productivity-related factors. The findings provide practical guidance for contractors, consultants, and project managers to improve productivity through better resource planning, workforce management, supervision, site conditions, payment practices, safety, and rework control.