We must reliably map the interactomes of cellular macromolecular complexes in order to fully explore and understand biological systems. However, there are no methods to accurately predict how to capture a given macromolecular complex with its physiological binding partners. Here, we present a screening method that comprehensively explores the parameters affecting the stability of interactions in affinity-captured complexes, enabling the discovery of physiological binding partners in unparalleled detail. We have implemented this screen on several macromolecular complexes from a variety of organisms, revealing novel profiles for even well-studied proteins. Our approach is robust, economical and automatable, providing inroads to the rigorous, systematic dissection of cellular interactomes.