ABSTRACT Overview: Proteomics, metabolomics, and lipidomics are critically essential techniques in cancer research. The Mass Spectrometry Shared Resource (MSSR), presented as a new UCCC SR in this application, supports UCCC members by utilizing mass spectrometry technologies to characterize a wide range of molecules in cancer biology applications. Services and Expertise: The primary focus of the MSSR is to provide the equipment and staff expertise to support application of, and education in, a range of MS-based methods. The MSSR mission is supported by a highly knowledgeable staff with >80 years combined experience in analytical methods to support biomedical research. Equipment: The MSSR houses 10 mass spectrometers, enabling global and targeted analysis of simple to highly complex biological samples. Management: The MSSR is co-directed by Dr. K Hansen (THI), a biochemist and proteomics expert who leverages mass spectrometry studies to investigate the tumor microenvironment, and Dr. A D'Alessandro (MCO), a biochemist and metabolomics expert who leverages MS to study cellular reprogramming in cancer and red blood cells. MSSR managers Dr. J Reisz Haines and Dr. M Dzieciatkowska collectively have >40 years of experience in Mass Spectrometry in academia and industry. Use of Services: Since July 2016, the MSSR has supported 268 investigators, including 55 UCCC members, 42 investigators from other NCI cancer centers, 152 other academic researchers, and 19 researchers at biotech organizations. UCCC members from all four programs have used MSSR services accounting for 38% ($971K) of total revenues over the period ($2.6M) and resulting in 56 cancer-related publications. Operating Budget: In the proposed budget model, CCSG funding represents 13% of the total ($1.2M) with the remaining from user fees (72%) and institutional support (15%). Innovation and Developments: The MSSR continually innovates and expands services to address evolving user needs and new opportunities in biomolecule characterization. In the most recent funding period, the MSSR added new services (e.g., crosslinking MS, metabolic flux analysis on as few as 250 cells) and equipment (Orbitrap Fusion Lumos and an inductively coupled plasma [ICP] MS), established a library of standards to enable quantitative measurements, and rapidly implemented remote operation for all staffing to ensure uninterrupted service during the COVID-19 pandemic. Future Directions: The MSSR will continue to provide support for MS-based research by UCCC members through acquisition and deployment of cutting-edge equipment, development of new methods, and expansion of training. To remain competitive, we will: i) develop a high-throughput plasma proteomics platform, building upon our acquisition of a 4D MS system (Bruker timsTOF Pro) and ii) increase throughput capabilities with the purchase of an Orbitrap Exploris and at least one high-parameter MS system for proteomics.