Agglomeration of particles in composite polymeric materials is a fundamental issue, but the relationship between the particle distribution and the composite mechanical properties is not fully understood. The ultimate goal of this study is to evaluate the effect of particle agglomeration upon mechanical properties of the composite. To achieve this goal, a colloidal crystalline array was encapsulated within a polymer matrix to make a model composite that has a well-ordered particle distribution. We characterized the particle distribution within the polymer matrix experimentally using Bragg diffraction of visible light and compared it with the interaction potential calculated by the Derjaguin-Landau-Verwey-Overbeek theory. Then, apparent cross-link densities of the composites were characterized from both swelling and mechanical measurements. Finally, the dynamic mechanical behavior of the composites with different particle distributions was analyzed. These data suggest that the particle distribution in the polymeric matrix plays ail important role in the composite mechanical properties.