The article considers an integrated evolutionary and epidemiological framework for human influenza B viruses. Topics discussed include the influence of viral, host, and ecological factors on the spatio-temporal incidence and evolution of human influenza viruses, the analysis of over 900 full genomes from an epidemiological bank of more than 26,000 strains obtained from Australia and New Zealand and the differences in the phylodynamics of two co-circulating lineages of influenza B virus.