Maintaining consistent cell growth and antibody quality during scale-up from lab-scale to commercial-scale bioreactors remains a critical challenge in biopharmaceutical development. Differences in mixing, mass transfer, shear stress, and control strategies can significantly impact cell physiology and critical quality attributes. This topic examines the key factors that drive variability across scales and how they influence productivity, glycosylation, and product stability. It highlights strategies for achieving scale-independent performance, including robust process design, predictive scale-up models, and enhanced monitoring and control. Addressing these challenges is essential to ensure reliable manufacturing, regulatory compliance, and seamless transition from development to commercial production.