This chapter surveys arguments for Kyd’s hand in Edward III and argues against the idea that Shakespeare revised a play written by another dramatist/s, for internal evidence suggests that Shakespeare planned and composed the play with Kyd. The Reign of King Edward III was entered in the Stationers’ Register on 1 December 1595 by Cuthbert Burby. It was published the following year with no allusion to the play’s authors or by which acting company it had been ‘sundry times played about the City of London’. On the basis of internal evidence, Shakespeare’s hand in Edward III is now universally accepted in modern authorship studies. This chapter reveals that the ‘non-Shakespearian’ scenes are commensurate with Kyd’s authorship and that this attribution has been anticipated by numerous scholars. The chapter expands upon previous scholarly observations through analysis of rhyme, prosody, and language in Edward III and in comparison to plays assigned to Kyd. The chapter proceeds to examine the ways in which this collaboration influenced the development of Shakespeare’s style and dramaturgy, using Henry V as a case study.