The Objects of the Order are charitable and educational and shall specifically serve to (1) encourage the study of the life and contributions of William the Marshal, First Earl of Pembroke; (2) accomplish research; (3) preserve manuscripts, wills, deeds, and other documents regarding his life; (4) support the restoration of sites and landmarks associated with William the Marshal, having charitable, literary, educational, historical, or governing backgrounds; and (5) promote patriotism and the art of chivalric behavior for ladies and gentlemen.
An invitation to apply may be extended to persons of all ages who are descended via an approved gateway ancestor, from William the Marshal, First Earl of Pembroke, and who are in support of the Order's Constitution and Bylaws. Life Membership is available for eligible persons of all ages. Members who have reached the age of eighteen have the privilege of voice, vote, and eligibility for appointment to the Curia Regis.
Link: https://www.orderofwilliamthemarshal.org