The Macromolecular Interactions Facility (MIF) in the Department of Biochemistry and Molecular Biology and Bio21 Institute at the University of Melbourne is a collaborative platform technology resource for the biophysical characterisation of proteins and other macromolecules. It brings together state-of-the-art instruments for the analysis of protein size, shape, secondary structure, interactions and complex formation. The equipment is open to all academic and commercial users, and training is provided. Instruments in the facility include analytical ultracentrifuges, a circular dichroism spectrometer, isothermal titration calorimeter and biolayer interferometer. Importantly, the analytical capabilities of our instruments also extend beyond proteins and have been successfully exploited for the study of drug binding, intracellular aggregation processes, nanoparticles and other systems.