This chapter examines the critical relationship between wave farm layout design and economic feasibility of ocean wave energy projects. The spatial arrangement of wave energy converters (WECs) within a farm significantly influences both energy capture efficiency and project economics through its effects on infrastructure requirements, installation procedures, and maintenance operations. Understanding the complex interplay between technical design considerations and economic implications is essential for developing commercially viable wave energy projects that can compete with other renewable energy technologies in the global energy market. The chapter begins with an introduction to wave farm layout fundamentals, exploring basic concepts and historical approaches to spatial arrangement of WECs. Section 4.2 delves into crucial design considerations and constraints, including hydrodynamic interactions between devices, environmental impact limitations, navigational safety requirements, and mooring system configurations. Section 4.3 presents methodologies for layout optimization focusing on cost efficiency, covering analytical frameworks for levelized cost of energy calculations, multi-objective optimization techniques, and economic implications of different spatial arrangements. Finally, Sect. 4.4 provides illuminating case studies from existing wave energy projects worldwide, offering practical insights into the technical and economic trade-offs observed in real-world implementations across various scales, technologies, and oceanographic conditions.