During the 19th century the European states experienced a new kind of threat to their existence. The military threats from other countries were now accompanied by civilian threats that inspired mass protest, terrorism and other menaces to the established order. In Sweden, these threats were mainly seen as connected to the rising labor movement and to a growing number of foreign citizens. The aim of the dissertation is to examine surveillance for national security carried out by the Stockholm Criminal Investigation Department and its Police Bureau between 1885 and 1922. Apart from examining what specific surveillance methods that were used, the dissertation gives an answer to the question why the surveillance was carried out, and why it was carried out the way it was. It also discusses how differences and similarities between the surveillance in Sweden and other countries can be explained and how the surveillance between 1885 and 1922 relates to the corresponding activities during the latter part of the 20th century. The main conclusions are that there was a lack of formal rules regulating the surveillance, and that it therefore was based on the following of routines. The bureaucratization process that characterized the period influenced the surveillance, which came to be performed as a bureaucratic machine, characterized by a tendency of expansion. This meant that the surveillance activities were constantly expanded and became more and more extensive. The expansion is connected to the surveillance phenomenon, which could be said to have an unlimited scope. Furthermore, it is suggested that this specific historic legacy has affected the development of Swedish security police activity during the second half of the 20th century.