Despite over 100 years of research on mosquito-borne pathogens, our knowledge of vector-virus-vertebrate interactions remains incomplete. Over the last 25 years, many of the viruses transmitted by mosquitoes have been associated with increasing numbers of human cases and expanded geographic ranges. Examples include the 1999 introduction and establishment of West Nile virus in the Americas, the almost global spread of chikungunya and Zika viruses during the early-mid 2000s, and the 2022 introduction of Japanese encephalitis virus into Australia. Since there are relatively few approved efficacious vaccines to protect people from infection with vector-borne viruses, both traditional and recently-developed methods to reduce the incidence of vector-borne diseases, continue to focus on controlling vector populations. A better understanding of the determinants and influencing factors involved in mosquito species-specific susceptibility to infection with viruses, and viral genetic determinants of infectivity for mosquitoes, could provide new opportunities for disease control. With references to published experimental data, the presentation will review and discuss some of the recent discoveries in the fields of vector biology and virology that are advancing our knowledge and understanding of the infection, dissemination, and transmission processes. Gaps in our knowledge of the virus-vector relationship, that remain to be filled will also be discussed.