In this paper, a comparative study is performed for a symmetrically laminated composite cantilever beam with and without a tip mass under harmonic base excitation. The base is subjected to both°apwise and chordwise excitations tuned to the primary resonances of the two directions and conditions of 2:1 autoparametric resonance. In the literature, the governing nonlinear equations of the same problem without tip mass have been derived using the extended Hamilton's principle. Extension is made in this study to include the e®ect of a tip mass on the response of the beam. The natural frequencies are obtained numerically using the diversity guided evolutionary algorithm (DGEA). Next, the multiple scales method is applied to determine the nonlinear response and stability of the system. A set of four¯rst-order di®erential equations describing the modulation of the amplitudes and phases of interacting modes are derived for the perturbation analysis. For veri¯cation, the above equations are reduced to the special case of the cantilever beam without tip mass for comparison with existing results. Finally, the e®ect of the tip mass on the stability of the¯xed points and on the amplitude of oscillation about the equilibrium points in both the frequency and force modulation responses is examined.