Our current understanding of a/~ T cell receptor (TCR) ex pressing T cells advanced from function and specificity to the molecular organization ofthe TCR.We now know that the TCR a and ~ chains together express specificity for (antigenic) peptides presented by the "responder" M H C allele, thus explain ing the phenomenon of MHC restriction at a molecular level. Surprisingly even though our perception of the molecular organization of the y5 TCR is well advanced, current knowledge of function and specificity of the y5 T cell subset is poor. There fore it appeared rather timely to bring together scientists pioneering research on y5 T cells forthe International Workshop on Function and Specificity ofy5 Tcells,held October11-14, 1990 at Schloss Elmau/Bavaria, FRG. Besides offering a scientific forum for open discussions, it was also hoped that such a workshop would be seminal for collaborative interactions and personal relationships among scientists "addicted" to y 15 T cells.