As part of IWA's role to promote networking and career development opportunities for young researchers and professionals, IWA established the Young Researchers Conference (YRC) in 2002 as a biennial international forum for young water professionals to discuss current and future environnmental concerns and network with peers from different research institutions, disciplines and countries. The selection of papers in this special issue of IWA Publishing's "Water and Environmental Management Series" represents papers that were presented at the 3rd Young Researchers Conference (YRC06) held on the 24-26 of May, 2006 at Nanyang Technological University, Singapore. The 58 papers from 23 countries were selecteed from 238 submissions and illustrate various aspects of water and wastewater engineering, technology and management, including chapters on:Wastewater TreatmentWater Policy and ManagementSludge Management and Waste TreatmentMonitoring and Data AnalysisModellingWater Quality and Wastewater Treatment Wastewater Biotechnology