HSN activities can be divided into three categories:
- projects aimed at enlarging the basic data file to cover the whole of the Netherlands (broadening);
- projects extending the data on individuals by using new sources (deepening);
- developing software and preserving the expertise in data gathering and research.
The border between broadening and deepening is not always clear when it comes to research projects. The basic HSN database consists of data from birth certificates, death certificates of those who died young, and personal cards of those dying between 1940 and 1994.
In a second phase, more material will be gathered from death certificates of those dying before 1940, marriage certificates, and population register entries. Most projects in cooperation with other institutions deal with the objective of deepening the material. Sometimes additional sampling is being carried out to secure sufficient records for specific research questions. Moreover, additional sampling is not a necessity based on the birth certificates.