Alexandre Popoff’s presentation, “Transformational Music Theory: From Group Theory to Film Music Analysis, and Beyond,” ties together algebraic formalizations of the neo-Riemannian triadic transformations with transformational analyses of film music. After reviewing Lewin’s notion of duality between transformation groups (and previewing a description of such duality using category theory), Popoff suggests some ways in which excerpts from film music make use of the formal properties of the neo-Riemannian transformations. Popoff draws numerous analyses from the music theory literature on film music (especially Lehman’s Hollywood Harmony: Musical Wonder and the Sound of Cinema [Oxford University Press, 2018]), and highlights ways that these harmonic relationships are made possible by formal aspects of the triadic transformations. For example, he draws on the fact that the operations in dual groups commute to show that a progression consisting of transformations from the PLR group can be recontextualized at different transposition levels. After providing several examples of specific transformations and describing their extra-musical meanings, he uses the tonnetz to visualize their parsimonious properties and relationships to diatonic collections. Popoff uses the networks in these analyses as motivation to summarize his work with Moreno Andreatta and Andrée Ehresmann (MCM 2015) which uses category theory to generalize Klumpenhauwer networks. In addition to the 90-minute recorded presentation, Popoff provides seven additional brief videos, each of which illustrates a specific triadic transformation using numerous clips from the music and film literature.