Dynamics of Coupled Structures, Volume 4. Proceedings of the 33rd IMAC, A Conference and Exposition on Balancing Simulation and Testing, 2015, 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 Structural Dynamics, including papers on:  Substructuring and the Ampair Wind Turbine Test Bed Experimental Dynamic Substructuring Reduced Order Models Experimental Studies of Joints and Joined Structures Analytical/Numerical Modeling of Joints Industrial Applications of Substructuring