Genetic psychophysiology examines interindividual variation in psychophysiological traits using behavioral genetic and molecular genetic techniques. It aims to delineate the pathways that lead from genomic variation to individual differences in cognitive abilities, affect regulation, and mental and physical health. This editorial provides an introduction to the twin design and gene finding strategies using psychophysiological endophenotypes. It also gives a brief outline of the papers presented in this special issue on genetic psychophysiology. Its main objective, and the objective of the entire special issue, is to interest psychophysiologists in the enormous potential of research in this area and to foster the development of collaborative relationships between psychophysiologists and molecular and behavioral geneticists that are necessary to move research in this area forward. © 2002 Published by Elsevier Science B.V.