Ingolf Dahl (1912-1970) was an American composer, conductor and pianist of German-Swedish parentage. Dahl emigrated to the United States in 1939 and was appointed to the faculty of the University of Southern California in 1949, a post he held until his death. Famed clarinetist Benny Goodman commissioned a double concerto from Dahl for performance by himself and English clarinetist Reginald Kell. The resulting work, Symphony Concertante for two clarinets and orchestra, was completed on December 6, 1952. Dahl's dissatisfaction with the final result led to a series of revisions to shorten the piece over the next eighteen years. Unfortunately, Dahl never heard Symphony Concertante performed in his lifetime. This dissertation centers around the creation of a new critical performance edition of Symphony Concertante. It begins with a brief look at the biography and compositional style of Ingolf Dahl, followed by the historical aspects of Symphony Concertante and other clarinet works by Dahl. The next portion of the paper focuses on the revisions made to the piece and the challenges they presented when making this edition. The process for dealing with these discrepancies is outlined in the Edition section, complete with examples of the main corrections found in this edition. A detailed analysis of each movement is given with particular emphasis placed on Dahl's usage of form and thematic material. The edition of the score itself is provided, with Appendixes describing the source material and a complete list of emendations to the score.