To conclude, we offer the following list as our take home message to encourage best practices and avoiding past pitfalls that have plagued molecular genetic investigations of complex traits. We believe that future endophenotype research will be most profitable if investigators consider these points in the design and conduct of their research. Most endophenotypes only meet threshold criteria. Most endophenotype research is confined to establishing whether an electrophysiological variable meets the threshold criteria in Section I of Table 1. Hence, other than increasing the list of variables with endophenotype potential (see Table 5), endophenotype research has underperformed in its promise to deliver insights into the etiology of psychiatric disorders.The very definition of an endophenotype should evolve. The Gottesman & Gould (Irving I Gottesman & Gould, 2003) endophenotype criteria have proved monumentally valuable for stimulating research on endophenotypes, but we believe the time is ripe to adopt the criteria in Table 1 as an aid to further advance the field. It is time to define an endophenotype as a biobehavioral trait that not only identifies genetic liability for a disorder, but
