This chapter sets out to trace the origin of the idea of double righteousness (duplex iustitia) that underlies Article 5. It examines various versions of duplex iustitia teaching prior to the Regensburg Colloquy, especially that of Luther, Pighius, Gropper, and Bucer. It then traces the approach to the idea after the colloquy, looking especially at Contarini, Gropper, Luther, Bucer, Calvin, and the Tridentine Decree on Justification. It then contrasts double righteousness with double justification. The latter has three distinct meanings. There is the Catholic contrast between the initial justification of the ungodly and the subsequent justification of the godly; there is the idea of the justification of works as well as persons, held by both Protestants and Catholics; there is the idea of the double formal cause of justification, held by Contarini and Gropper. None of these is found in Article 5.