The program aims to reach recreational drug users through the provision of an on-site service: The combination of outreach social work and chemical analysis of substances directly at rave parties as well as providing information on safer use and counseling.The general objective of the project is the prevention of problematic consumption patterns regarding psychoactive substances and prevention or reduction of short, middle and long term adverse health consequences (selective and indicated prevention, harm reduction). checkit! is a scientific project aimed at collecting scientific data. Through documentation of the chemical analysis and the distribution of user surveys - focusing on patterns and reasons of use - essential data for the early detection of new trends regarding substances and their use is obtained. Based on the data preventive methods and offers are developed continuously.The interest expressed by intense use of the services shows that information can be accepted as it is presented in an objective and target group specific way.People involved in drug testing have a higher knowledge and this knowledge increases with increasing number of pilltesting activities. But no change in behaviour was found.