The P41 Resource for Native Mass Spectrometry Guided Structural Biology (nMS->SB Resource), established in 2018, is a national Biomedical Technology Research Resource that seeks to develop and disseminate novel research technologies and methods for structural biology. The Resource is developing and disseminating a suite of technologies under five Technology Research and Development (TR&D) projects; these include (TR&D 1-3) novel surface-induced dissociation (SID) cells coupled to high-resolution ion mobility (IM) and high-resolution mass spectrometry (HRMS), (TR&D 4) online purification and separation schemes, and (TR&D 5) computational tools for structure determination from experimental nMS data. The Resource has successfully supported the efforts of numerous biomedical researchers across the country and the globe to characterize a variety of noncovalent protein and RNA/DNA:protein complexes, including synthetic amyloid beta (Aβ) and tau aggregates, novel de novo designed protein complexes from the Baker laboratory (University of Washington), orthologous 20S proteasomes expressed by the Sharon laboratory (Weizmann Institute) and recently Ebola virus matrix protein VP40 (La Jolla Institute of Immunology). Our protein:protein and nucleoprotein complexes are typically run at mass spectrometry-friendly concentrations and in mass spectrometry-compatible buffers/ electrolytes. Acquisition of an instrument (Refeyn OneMP Mass Photometer) for light-based mass photometry (interferometry) measurements will provide new technology for our DBP and C&S investigators, allowing us to assess small sample volumes at very low concentrations (pM to low nM). Mass photometry (MP) will provide a quick screen of sample quality and oligomeric distributions present in the sample in the investigator’s provided storage buffer, allowing MS team members to decide on the appropriate next steps for the sample. We will determine whether the sample will go back to the investigator for improvements or whether it is ready for higher resolution, higher mass accuracy native mass spectrometry measurements. For a wide variety of protein complex types, provided by a broad set of DBP and C&S projects, we will establish complex types and concentration behaviors for which the MP and nMS results are duplicative and those for which the two sets of results provide additive/complementary data to characterize the complex more fully over a large range of conditions (oligomerization time/kinetics, concentrations, buffer conditions).