A major focus of Dutch addiction policy is to improve the monitoring of substance use and addiction - which surveys and registrations are important for the monitoring of alcohol and drugs problems, and what information is generated or needs to be generated by these monitors? Three methods were used: an inventorisation of existing monitoring projects, a survey among experts in the field of alcohol and drugs to study the information needs, and a study on the output and shortcomings of the existing monitors. Sixty monitors and 13 'umbrella' monitors were found. Experts formulated the needs of 11 topics which were matched with the output of the monitors. Coverage of the nature and extent of use in general is good. Shortcomings apply to the use and accessibility of the monitors, as well as to their completeness, standardisation and content. Especially questions with respect to problem use, treatment demand/need of help and user careers cannot be answered sufficiently with the existing information.