This chapter presents a comprehensive treatment of open front inclined apron feeders used for the controlled discharge of run of mine (R.O.M.) ores into primary crushers. These feeders are essential where large lump sizes and wide particle size distributions preclude the use of conventional gating systems. The chapter describes the functional feed zones of the inclined apron feeder and develops analytical performance equations for throughput, loads, torque and power based on continuum theory and mass flow principles. Emphasis is placed on the contribution of hopper geometry, shear mechanisms and skirt plate friction to overall resistance. To validate the analytical approach, results from pilot scale model testing are presented and interpreted using dimensional analysis and dynamic similarity. Non dimensional performance parameters are introduced, enabling reliable scaling from model to full scale industrial feeders. A full scale case study is used to demonstrate application of the methodology and to highlight key design sensitivities. The chapter concludes by showing how combined theoretical analysis and model testing provide a robust framework for the design and optimisation of large inclined apron feeders.