This report presents the results and outlines the key achievements and challenges faced by mechanism set up by the Council Decision in 2009. In 2009, 24 new psychoactive substances were officially notified for the first time in the European Union through the Early-Warning System (EWS). All new compounds were synthetic, including two substances with medicinal properties. Nine of the reported substances were synthetic cannabinoids from four distinct chemical groups. Beyond these, there was a mix of substances belonging to more established chemical families – five phenethylamines, two tryptamines and four synthetic cathinones. No new piperazines or psychoactive plants were reported. The report also highlights the emergence of new, smokable herbal products laced with synthetic cannabinoids and the growing popularity of various synthetic cathinones as significant new developments in the field of so-called ‘legal highs’. Furthermore, the report includes a brief follow-up on the piperazine derivative mCPP, a brief threat assessment, a review of the EWS achievements, and a look into some of its challenges.