The present invention provides targets, methods, and reagents for the diagnosis and treatment of schizophrenia and related conditions. The invention provides methods for the diagnosis of schizophrenia and susceptibility to schizophrenia by detection of polymorphisms, mutations, variations, alterations in expression, etc., in genes encoding an EGR molecule or an EGR interacting molecule, or polymorphisms linked to such genes. The invention provides oligonucleotides, arrays, and antibodies for detection of polymorphisms and variants. The invention provides transgenic mice having alterations in such genes. The invention also provides methods of treating schizophrenia by administering compounds that target these genes. The invention further provides screening methods for identifying such compounds and compounds obtained by performing the screens.