S&T indicators can have a number of objectives in science and technology policy, of which monitoring and evaluation are the most important. The development of S&T indicators is described in relation to different periods of Dutch science policy. Before a more optimal situation can be created, certain conditions should be met, which are related to three levels of communication — policy, data infrastructure and intermediate. The Netherlands Observatory of Science and Technology acts as a bridging mechanism betwveen the policy system and the data infrastructure system. The main objective of the current indicators is to monitor the S&T system in a general way, but it will be necessary to optimise the potential of S&T indicators to generate information that can be used in more specific discussions on S&T policy.