In recent days, wing kits are extensively used to convert conventional munitions into guided munitions. The wing kit integration enables munitions to gain standoff attack capability, extends their range and together with a laser guidance system, adds moving target tracking capability. Typical wing kits are usually composed of two main wings, however, some of them have a joined-wing configuration where the aft wings can support the main wings in order to increase maneuverability, range performance and structural performance. In this study, since the geometry and sweep angle of front wings are kept fixed due to aerodynamic effects in operating conditions, joined-wing configurations are investigated by changing two key parameters, namely; aft wing sweep angle and location of the joint. Response surface methodology is used in order to determine how these parameters affect the vibration characteristics of the joined-wing configurations. In numerical analyses, the natural frequencies and the corresponding mode shapes for the configurations are obtained by using ANSYS software. Then the results of selected configurations are verified via modal testing so as to achieve accurate finite element models of the joined-wing configurations.