This report presents the results of the EDRS (formerly known as the Party Drugs Initiative (PDI), a study undertaken to monitor ecstasy and related drug markets in South Australia. 2009 was the tenth year in which regular ecstasy users in Adelaide have been surveyed, and comparisons with previous years have been drawn where possible. Trends in the demographic characteristics and patterns of drug use among regular ecstasy users (REU), the prevalence of risk-taking and harms related to drug use, as well as the level of criminal involvement among this group, are presented. Also presented are details on current price, purity and availability of ecstasy and related drugs in Adelaide, together with the trends in these drug markets.