Dynamics of Coupled Structures, Volume 4: Proceedings of the 42nd IMAC, A Conference and Exposition on Structural Dynamics, 2024, the fourth volume of ten from the Conference brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of the Dynamics of Coupled Structures, including papers on: Linear Joints, Nonlinear Joints and Coupling Modal and Frequency Based Substructuring Round Robin Test Bed on Dynamic Substructuring Transfer Path Analysis and Force Estimation Interface Dynamics