Sean Costello is a resident of Marshfield and a graduate of Marshfield Public Schools, with over a decade of professional experience in both state and local government.
For over 10 years Sean worked at the Massachusetts State House for Representative Bruce Ayers, first as Legislative Director and later as Staff Director. In this role, Sean helped increase healthcare access for people with early-onset Alzheimer’s disease and dementia; expand water transportation services in Quincy and Boston Harbor; and secure funding for veterans’ substance use addiction treatment and counseling services, among other successful policy initiatives.
Sean was elected to the Marshfield School Committee in 2015, and was re-elected to his 4th term in 2024. He served as Chair from 2016-2021, and again from 2022-present. He is also a board member of the Massachusetts Youth & Government program.
Sean obtained his undergraduate degree in Political Science & International Studies with a minor in Grassroots Studies from Stonehill College in 2014. In 2023, he earned a Credential of Public Leadership from the Harvard Kennedy School of Government.