The present national and international trends about waste management favour recycling and recovery of waste either as materials or as energy. Therefore, it can be supposed that recycling activities of materials as for example the composting of urban waste organic fraction will be more and more encouraged in the future. Nevertheless, if we intend really to develop a market of recycling and recovery of waste, the quality of products obtained must be especially considered. As regards the compost, these problems have taken a great importance in the last years, since only high quality compost finds utilization in agriculture. In this paper, we investigate the procedure to carry out in order to obtain a compost of high quality either from a chemical, microbiological or technological point of view, by examining particularly the effects on compost quality, in consequence of separation of some specific waste streams at source.