A prototypical example of the photochromic system is azobenzene, undergoing trans ↔ cis isomerizations upon illumination with light in ultraviolet (UV) and visible regions of the electromagnetic spectrum. Arrangement of numerous azobenzene units in proximity to each other takes place in molecular crystalls, liquid crystalls, self-assembled monolayers (SAMs), micelles of azobenzene-containing surfactants, surfactant-polymer complexes, and other supramolecular systems and architectures. Distinct spectroscopic signatures (such as spectral shifts and changes in absorbance) originating from azobenzene aggregation have been observed experimentally, e.g., for SAMs and micellar solu-tions. Moreover, several studies have reported first-principles calculations of exciton states of azobenzene aggregates and SAMs. However, these studies address exciton states for fixed nuclear configurations of the aggregates. To go beyond this single-geometry picture, it is necessary to account for ground-state conformational (geometrical) disorder (induced by thermal fluctuations) and excited-state dynamical effects.