X-Modal III is an experimental modal analysis software package developed at the University of Cincinnati, Structural Dynamics Research Lab (UC-SDRL) in conjunction with The Boeing Company. The primary function of this software package is to provide a flexible environment for analyzing data acquired for the purpose of experimentally determining the modal parameters of a structure. The flexible environment involves a unique data management structure as well as a user programming capability based upon MATLAB. X-Modal III does not acquire frequency response function (FRF) data but utilizes FRF data acquired from any data acquisition system as long as the data can be provided in Universal File format (UFF). X-Modal III provides a graphical user interface (GUI) in parallel with a command driven interface to provide users with any type of programmatic interaction desired. X-Modal utilizes MATLAB to provide user programmability as well as to implement all the major modal parameter estimation algorithms documented in the literature.