The 2019 Massachusetts Department of Public Healths (MDPH) Arbovirus Surveillance and Response plan provides surveillance and phased response guidance for arthropod-borne viruses (arboviruses) affecting Massachusetts residents, West Nile virus (WNV) and eastern equine encephalitis virus (EEE), in particular. Since 2000, there have been 203 cases of WNV among Massachusetts residents resulting in at least 12 deaths and 26 cases of EEE resulting in at least 14 deaths. This plan reflects a comprehensive review of surveillance activities, mosquito control efforts, public information, and risk communication related to arbovirus control in Massachusetts. Key components of the plan include: monitoring trends in eastern equine encephalitis virus (EEE( and West Nile Virus (WNV) activity in Massachusetts; timely collection and dissemination of information on the distribution and intensity of WNV and EEE in the environment; laboratory diagnosis of WNV and EEE cases in humans, horses and other animals; effective communication, advice, and support of activities that may reduce risk of infection; 5. phased response to provide measures to suppress the risk of infection; and 6. monitoring for evidence of introduced and emerging arboviruses and new mosquito vector species.