CODECS (COnvergent Distributed Environment for Computational Spectroscopy) is an interdisciplinary COST action which aims at creating a network dedicated to computational spectroscopy, i.e. to the extraction of structural and dynamical features of molecular and supramolecular systems by in silico analysis of spectroscopic observables. The Action is organised in four Working Groups whose activities will cooperate to develop a general, integrated computational tool for resonance, vibrational, and optical spectroscopies based on multiscale computational approaches in space and time, at quantum, semi-classical and classical levels of description of structural/dynamic molecular phenomena.