Any woman is eligible for membership who is no less than eighteen years of age and can prove lineal, blood line descent from an ancestor who aided in achieving American independence. The National Society reserves the right to determine the acceptability of all service and proof thereof. The National Society accepts service, with some exceptions, for the period between 19 April 1775 (Battle of Lexington) and 26 November 1783 (withdrawal of British Troops from New York) as follows: Signers of the Declaration of Independence, Military Service, certain types of Civil Service (under authority of Provisional or new State Governments), and certain types of Patriotic Service. Admission to membership in the NSDAR is either by invitation through a state chapter or unit overseas.