Endohedral fullerenes in general and cluster/molecule encapsulated endohedrals in particular exhibit a very complex dynamic behaviour, that has necessarily to be considered when investigating or characterizing these systems by spectrosopic measurements. Molecular dynamics (MD) simulations along with the calculation of dynamic spectra provide a detailed insight into the intra‐cage dynamics of these systems and help to clarify its impact on spectroscopic investigations. The effects are shown exemplarily for Sc3N&at;C80, Sc3N&at;C78and Sc2C2&at;C84. © 2003 American Institute of Physics