Interpretation of sophisticated experiments often requires advanced theories. A consistent set of user-friendly tools for an elaborate treatment of nuclear motions of microscopic and macroscopic systems does not yet exist. Development of the armoury of first-principles nuclear motion theory, via the advancement of theories, algorithms, and codes, is the major goal of this Action, with special emphasis on quantum effects involving electrons as well as nuclei. Molecular scientists, modellers and engineers will all benefit from the new methods and codes. The developments cover quantum chemical, quantum dynamical, semi-classical, and advanced classical treatments. Access to most of the source codes developed within the Action is provided to the scientific community free of charge. Multifaceted collaborative efforts with experimentalists applying the pilot versions of the new tools is considered to be vital to the success of the Action. MOLIM is a platform for (a) development of an extensive, heavily interlinked collaboration network of theorists and experimentalists from more than 20 countries; (b) quick dissemination of important results to a large and growing scientific community; and (c) establishment of long-lasting EU-wide conferences and training schools, educating the next generation of users of the next generation of chemistry tools.