The Getty Trust Indenture dated December 2, 1953 made a California charitable trust for "the diffusion of artistic and general knowledge." The trust is governed by a 13-member board of trustees. Trustees are elected to serve four-year terms, with a maximum limit of three terms. The board is self-perpetuating with the board electing or re-electing the trustees. The board holds an annual meeting in May or June of each year. Although the board conducts most of its work through committees, a number of important decisions are reserved for the entire board including approval of any art acquisition costing more than $1 million.