A steady improvement in the economy and employment since 2010 did not stop the drop in total fertility rate in Finland. Declining fertility now includes women in almost all age and educational groups in the country. This decline has continued long enough to also indicate a dramatic decrease in completed fertility, which is a departure from decades of sustained levels of completed fertility. Drawing from a range of publicly available descriptive data, this article assesses the extent to which old and new theories of fertility are relevant in explaining this development. In conclusion, the fertility development in Finland is surprising, and challenges traditional theories on fertility, which analyse fertility from economic and gender perspectives. Social interaction theory holds more promise. However, it is very difficult to find data sources which could elucidate the role of social interaction in the fertility decline. Designing pro-natalistic policies is challenging before there is more detailed evidence and understanding concerning the key drivers of the fertility decline in Finland.