In RR spectroscopy, incident light E L of frequency Here we advance a method to quantify the overall decoherence and decompose it into contributions due to specific vibrational modes (b) and solvent (c), thus establishing decoherence pathways that link chemical structure with quantum decoherence. This is done by extracting the highly structured spectral densities for solvated molecules directly from resonance Raman experiments and using the theory of decoherence functions to isolate individual contributions by solvent and vibrational modes. The strategy opens exciting opportunities to unlock the chemical principles of electronic quantum decoherence.