This chapter explores scaling as a distinct and complex process, marked not just by growth in size but by efficiency, resource leverage, and strategic adaptation. It reviews leading definitions from OECD, Startup Genome, and the European Scaleup Institute, introducing concepts like Gazelles, Hypergrowers, and Consistent High-Growth Firms. The chapter then dives into conditions for scaling, such as product-market fit, market readiness, and dynamic capabilities. Key inputs include talent, capital, networks, and operational systems, all of which must be carefully orchestrated to support scale. Strategies for scaling, ranging from partnerships to internationalization, are examined alongside the role of entrepreneurial ecosystems and public policy. The chapter also addresses the effectiveness of accelerators, incubators, and other support entities in supporting the transition from startup to scaleup. Throughout, the authors emphasize that scaling is nonlinear, contextual, and highly dependent on execution.