2,3-Didecyloxyanthracene (DDOA) is able to gel a large variety of organic solvents at very low concentrations by forming a three-dimensional network of fibers. A vibrational assignment is proposed for the midinfrared absorptions of DDOA in the gel and solution states, showing that some out-of-plane vibrations of the anthracene group constitute pertinent local probes of the molecular organization in the three-dimensional supramolecular architecture. A model of the molecular arrangement of the DDOA molecules within the fibers is proposed from ab initio calculations combined with IR and fluorescence dichroism experiments performed on oriented bundles of aerogel fibers.