Abstract: T cell activation is based on interactions of T cell antigen receptors with MHC‐peptide complexes in a specialized cell‐cell junction between the T cell and antigen‐presenting cell—the immunological synapse. The immunological synapse coordinates naïve T cell activation and migration by stopping T cell migration with antigen‐presenting cells bearing appropriate major histocompatibility complex (MHC) peptide complexes. At the same time, the immunological synapse allows full T cell activation through sustained signaling over a period of several hours. The immunological synapse supports activation in the absence of continued T cell migration, which is required for T cell activation through serial encounters. Src and Syk family kinases are activated early in immunological synapse formation, but this signaling process returns to the basal level after 30 min; at the same time, the interactions between T cell receptors (TCRs) and MHC peptides are stabilized within the immunological synapse. The molecular pattern of the mature synapse in helper T cells is a self‐stabilized structure that is correlated with cytokine production and proliferation. I propose that this molecular pattern and its specific biochemical constituents are necessary to amplify signals from the partially desensitized TCR.