Within this topic NIVEL researches the health of the Dutch population. The data for this research is usually taken from the electronic patient files of primary care professionals and sometimes from ad hoc data collections. This topic contains various focus areas: acute illnesses are considered, but so are comorbidity; psychological complaints; the surveillance of influenza and other infectious diseases; health in deprived neighbourhoods and among migrants and refugees; and the effects of calamities and environmental conditions on the state of public health. The National Study of Illnesses and Care in the Primary Sector is given an important place in the research. This study refreshes the data on health and illness in the general public and in primary care, following the first and second Dutch National Surveys of General Practice. To achieve this, information infrastructure is built up, integrating the data sources of primary care professionals. By using the same instruments of measurement, historical developments can also be made visible in this infrastructure.