Nowadays, the concern about using organic waste as renewable energy sources is a critical worldwide issue. In this area, anaerobic digestion (AD) seems to be a promising solution because of significant reduction of waste quantity and generation of valuable products such as biogas, regarded to be a good energy carrier and digestate with high nutritional potential for agriculture. The current trends in anaerobic digestion focus on improving the efficiency of the process to make this a cost-effective treatment. Depending on the sources (agricultural, municipal, industrial), organic waste differs considering both its composition and structure, and thus the bioaccessibility and biodegradability of waste. Accordingly, carbohydrate-rich materials, protein-rich materials and fat-rich materials require different operational conditions to overcome technological problems and minimize the risk of disruption of failure of the anaerobic systems. Different strategies can be used to enhance the biogas production. They include: waste pretreatment (mechanical, thermal, chemical and biological), two-stage anaerobic digestion (temperature phased AD and two-phase AD), anaerobic co-digestion (two-substrate and multi-substrate systems) and bioaugmentation (with natural strains or specialized consortia of microorganisms and genetically modified microorganisms or their consortia). Some of them enhances its accessibility and digestibility, the others improve nutritional balance, metabolic properties and operational factors facilitating synergistic effect of microorganisms. The book covers the current developments in the area of enhancing biogas production.