Psaume 130, Du fond de l'Abime, by Lili Boulanger, poses a series of problems for conductors. Its large orchestral requirement and thirty-minute performance length severely limit the possibility of programming the work. Having thoroughly studied the composer's other works, I have determined that balance problems in the orchestration need adjustment. Errors exist in the current published edition and warrant correction.For these reasons combined with the assertion, later discussed in this document, that Lili Boulanger may have been asked to make a more practical version of Psaume 130, Du fond de l'Abime in order to promote sales of her music, an orchestral reduction is a viable solution. In addition, she died before the premier of the work and may have re-orchestrated certain passages upon hearing it.The methodology for this process of editing and rescoring includes:1) comparison of the manuscript with the published edition, 2) analysis, which includes tonal, motivic, and structural aspects of the work, 3) analysis of Boulanger's orchestral technique, and 4) an interview with conductor Mark Stringer.I will demonstrate that Lili Boulanger's Psaume 130, Du fond de l'Abime can be arranged for reduced forces while preserving its essential elements. This version will be more accessible for professional, college, community and church choirs, and orchestras.