Salinity Gradient (or Osmotic) Power is a renewable energy concept first proposed in the 1950s that has experienced a marked surge of interest over the past decade due to increased availability and improved performance of system components. This chapter outlines the most prevalent methods of harvesting Osmotic Power, including Pressure Retarded Osmosis (PRO), Reverse Electrodialysis (RED) and Capacitive Mixing (CAPMIX). It also examines the technology's potential based on availability of natural resources, and provides an insight into the current state of the technology. Current trends indicate that upscaling of salinity gradient processes to commercial level is most feasible for hybrid applications with desalination and/or wastewater treatment. This is largely because the variability in natural resource, high cost of materials and shortage of pilot-scale studies makes the upscaling of standalone plants an unappealing option for investment. Research is ongoing in development of components and materials tailored to each process to optimize power output, and requires investment in design and development before upscaling of standalone SGP plants is economically favorable. No definitive advantage of any conversion process over others has yet been found, though each has distinct advantages and disadvantages, and different methods will likely be more applicable than others for specific applications.