This work contains a new, updated and expanded edition of Rev. Dr. Matthew Everhard's dissertation entitled: A Theology of Joy: Jonathan Edwards and Eternal Happiness in the Holy Trinity. This paper was originally submitted to the faculty of Reformed Theological Seminary in Orlando as part of his doctoral studies. A Theology of Joy was originally published by the JESociety, but has since gone out of print. Now, it is being republished again alongside a number of shorter essays that have likewise been previously published elsewhere. All these works are being brought together and published in one volume for the first time. This new expanded edition is an exciting contribution to the field of Jonathan Edwards's studies and represents more than a decade of work and study by Matthew Everhard.