In accordance with the provision of the gift of Maria Cary establishing a public library in Lexington, the Board of Library Trustees consists of "the Selectmen, and the School Committee of the Town for the time being and the settled ministers of the place."
The Board of Library Trustees oversees the financial affairs, trust funds, fundraising activities and sets the policy for the operation of the Library.
The Trustees elect a five-member Executive Committee to oversee the financial and day-to-day operations of the Library. The Executive Committee consists of two officers of the Board of Library Trustees and three other Trustees. The Clergy, the Selectmen and the School Committee have at least one representative on the Committee. The Executive Committee has full power to act in all matters for the Board of Trustees.