This article describes the development of a valid and reliable instrument to measure different dimensions of public trust in health care in the Netherlands. This instrument is needed because the concept was not well developed,or operationalized in earlier research. The new instrument will be used in a research project to monitor trust and to predict behaviour of people such as consulting ‘‘alternative practitioners’’. The idea for the research was suggested by economic research into public trust. In the study,a phased design was used to overcome the operationalization problem. In the first phase, a qualitative study was conducted; and,in the second,a quantitative study. In the first phase,more than 100 people were interviewed to gain insigh...