The dynamic behavior of a bladed disc assembly was determined by developing a finite element model (FEM). The object of this work is to develop an understanding of the dynamic behavior of the system with respect to the various boundary conditions. The analysis included variation of the boundary conditions at the blade-disc interface, between adjacent blades, and the shroud. It was clearly shown that only certain mode patterns are affected with respect to a particular boundary condition, leaving the remaining modes unchanged. The quantitative effect of the various boundary conditions was calculated by finite element analysis of a cyclic symmetric model. A methodology is also presented where the associated modes of the higher harmonics natural frequencies of the assembly, are identified in a systematic and automated way without being plotted and viewed. This methodology which uses the cross-orthogonality equations, is valuable to systems with a large number of nodal diameters, where the complete set of the associated mode shapes can be analyzed in an efficient and systematic way. The technique is illustrated through an example, where a complete analytical Campbell diagram for the lower order modes is developed.