The Immunological Synapse, Part A, Volume 173 in the Methods in Cell Biology series provides state-of-the-art methods for the study of the immunological synapse. Sections cover Imaging polarized granule release at the cytotoxic T cell immunological synapse using TIRF microscopy: control by polarity regulators, Analysis of centrosomal area actin reorganization and centrosome polarization upon lymphocyte activation at the immunological synapse, P815-based redirected degranulation assay to study human NK cell effector functions, Cytotoxic and Chemotactic Dynamics of Natural Killer Cells Quantified by Live-cell Imaging, Quantification of interaction frequency between antigen-presenting cells and T cells by conjugation assay, and more. Other chapters focus on the Study of the Effects of NK-Tumor Cell Interaction by Proteomic Analysis and Imaging, Quantification of lymphocytic choriomeningitis virus specific T cells and LCMV viral titers, Quantification of lymphocytic choriomeningitis virus specific T cells and LCMV viral titers, An in vitro model to monitor natural killer cell effector functions against primary breast cancer, and Standardized Protocol for the Evaluation of Chimeric Antigen Receptor (CAR)-modified Cell Immunological Synapse Quality using the Glass-supported Planar L.