Germinal centers (GCs) are microanatomical sites of B cell clonal expansion and antibody affinity maturation. Driving the GC reaction are a specialized subset of T cells called T follicular helper (Tfh) cells. Tfh engage in cognate ineractions with GC B Cells, leading to GC expansion. However, it has become evident in later times that the GC harbors multiple subsets of T cells, and that they serve a role in controlling the rise and fall of the GC. We are investigating the role of different T cells in GC kinetics, and how this ultimately effects the quality of GC B cells.