This study is an examination of the institution of ordination to ministry of word and sacrament in the Presbyterian Church (U.S.A.), through the lens of the particular biblical-theological paradigm of diakonia, or servanthood. Chapter titles include: 1) Biblical Roots of Ordination 2) The Evolution of the Threefold Pattern of Ministry 3) Luther and Calvin on Ordination 4) Ordination in the Scottish Reformation 5) The Developing American Understanding of Ordination 6) Recent American Developments 7) A Contemporary Presbyterian Statement on Ordination. This study traces the concept of diakonia as a controlling paradigm for the understanding of ministry in the Presbyterian Church (U.S.A.). Following a survey of biblical writings on ordination and ministry, it traces the rise of the "threefold pattern" of bishop, presbyter and deacon through the first three centuries of the church, then explores how the first-generation reformers Luther and Calvin discarded these forms in favor of a radically functional view, informed by the biblical concept of ministry as diakonia. This functional, servanthood model of ministry is traced through the Scottish reformation, to the new world, to recent developments in the Presbyterian Church (U.S.A.). The final chapter is an attempt to creatively state the essentials of the Presbyterian understanding of ministry as servanthood.