This article discusses relational ontology and its significance for interpreting archaeological material from post-medieval contexts. The general theory of the relational constitution of the world is first introduced and some of its implications discussed in relation to the ‘meaning’ of artefact biographies. Second, by drawing from folk beliefs, the article considers how people in early modern Finland recognized the relational constitution of the world, which in turn provides new insights into the local mode of perceiving and engaging with the material world. The case of household spirits and human relationship with buildings is taken as an example. The archaeological material discussed in the article derives from the seventeenth-century town of Tornio in northern Finland.