Composting is increasingly used as a recycling technology for organic wastes. Knowledge on the composition and activities of compost microbial communities has so far been based on traditional methods. New molecular and physiological tools now offer new insights into the "black box" of decaying material. An unforeseen diversity of microorganisms are involved in composting, opening up an enormous potential for future process and product improvements. In this book, the views of scientists, engineers and end-users on compost production, process optimisation, standardisation and product application are presented.