We are pleased to invite you to the fifth conference on the Ecology of Soil Microorganisms, held again in Helsinki. This scientific event addresses questions related to individual microbes, i.e., archaea, bacteria, fungi, oomycetes, protozoa, viruses as well as microbial communities and their ecological networks. The aim of the conference is to advance understanding of the complex interactions across scales-from soil microbes and their viruses to their relationships with plants and larger ecosystem processes. The conference program shows that understanding of soil microbiology and processes is increasingly expanding from amplicon-based analysis to sequencing of metagenomics, metatranscriptomics and proteomics as well as different in-situ and single-cell measurements. The new era of improved molecular analytics allow simultaneous analysis of soil viruses and invertebrates in addition to bacteria. We look forward to this trend which will eventually provide us with a new understanding of the truly complex networks of soil microorganisms and their functioning. The organizers, together with the Natural Resources Institute Finland, warmly welcome experts from all related disciplines to join this state-of-the-art research forum and enjoy the unique atmosphere of Helsinki’s Northern midsummer.