This North Atlantic Treaty Organization (NATO) Advanced Research Workshop (ARW) was devoted to Wastewater Reuse – Risk Assessment, Decision-Making and Environmental Security held in Istanbul, Turkey, at the Hotel Villa Suites, Taksim during October 12–16, 2006. More than 100 scientists had requested to parti- pate but only 63 could attend the meeting representing 20 countries—Azerbaijan, Canada, Czech Republic, Egypt, Greece, Italy, Israel, Jordan, Kyrgyzstan, Lithuania, Portugal, Romania, Spain, The Netherlands, Tunisia, Turkey, Turkmenistan, Ukraine, United States of America, and Uzbekistan. 48 papers and 10 posters were presented; only 45 research papers were selected and put in this proceedings manual. Other papers, although they had good information, could not be included due to poor data, not related to the topic or failed to meet the deadline. You may feel some difficulty in understanding some of the papers due to the fact that they were initially written in presenter’s home language and then translated into English by nonscientific people, who have very little knowledge or interest in putting correct scientific terms. Financial support came from the NATO Program for Security through Science, Public Diplomacy Division and sponsored by the Society of Risk Analysis (SRA). Twelve (12) individual participants contributed towards their travel and two (2) for their living expenses.