ABSTRACT Support is requested for a Keystone Symposia conference entitled T and B Cell Collaboration in Germinal Centers and Beyond, organized by Drs. Shane Crotty, Michela Locci and Jennifer Gommerman. The conference will be held in Whistler, British Columbia, Canada from October 1-4, 2023. T cell/B cell interactions are fundamental for numerous immune responses. And, as the COVID-19 pandemic demonstrated, the successful development of COVID-19 vaccines highlighted the extreme value of T and B cell interactions for protective immunity. For example, the development of antibodies able to neutralize variants as diverse as Omicron, after not one or two but after three other mRNA immunizations, with the same ancestral SARS-CoV-2 Spike, is a dramatic example of the importance of germinal centers in protective immunity, and the brilliance of the immune system in rapidly evolving T-dependent B cell responses capable of neutralizing extreme viral variants the cells never previously encountered in the germinal centers. However, there remains much to be learned about the critical importance of T cell/B cell interactions and germinal centers for vaccines and infectious diseases. Furthermore, the relevance of these immunological interactions is much broader in biomedicine. T cell/B cell interactions are important in many autoimmune diseases. Moreover, this conference will be held jointly with the Keystone Symposium on B Cells and Tertiary Lymphoid Structures: Emerging Targets in Cancer Therapeutics and there will be joint sessions covering T cell/B cell interactions in cancer.