Historical datasets often impose the need to study groups of people based on occupation or social status. This paper presents first results in creating an ontology of historical Finnish occupations, AMMO, that enables selection of groups of people based on their occupation, occupational groups, or socioeconomic class. For interoperability, AMMO is linked to the HISCO international historical occupation classification and to a late 20th century Finnish occupational classification. AMMO will be used as a component in two semantic portals for Finnish war history.