This study aims to examine the ways in which English composer Edward Elgar (1857–1934) expanded common-practice tonality; it shows how Elgar employed harmonic structures and syntax in an innovative manner through specific extended-tonal techniques such as the use of chromatic-third relations (both harmonically and as a tonal plan), harmonic substitutions, and local ambiguous sonorities that at times lead to tonal ambiguity. The system that Elgar expanded upon has been called “Classical diatonic tonality”, which was extended when late nineteenth-century composers such as Elgar infused their music with chromaticism. Through an investigation of Elgar’s extended tonal techniques one can come to a better appreciation of his late nineteenth-century harmonic vocabulary. It has been well documented that Elgar modeled his music after that of Wagner and his Germanic contemporaries (from Mendelssohn to Brahms), so that the Elgarian tonal language is one possible projection of a post-Wagnerian extended-tonal discourse. The discussion presented here will survey those parts of Elgar’s tonal language that he learned from his Germanic contemporaries, thereby establishing the context for his own unique chromatic compositional style. This study of Elgar’s work therefore further represents a study of the broader impact of post-Wagnerian chromaticism on late nineteenth-century English extended tonality.