Reliability and validity data on a procedure for identification of students "at risk" for exhibiting behavior disorders are presented. The Systematic Screening for Behavior Disorders instrument relies upon teacher judgment and normative criteria in three interrelated stages that cross validate the results of each other. Stage 1 has teachers rank students on both "externalizing" and "internalizing" behavioral dimensions. Stage 2 involves teacher completed rating measures on adaptive and maladaptive behavior while Stage 3 includes observation in classroom and free play settings which are used to confirm other measures. Data are presented on a districtwide trial involving 158 classroom teachers in 16 schools. Observation data on 301 elementary grade students confirm the accuracy of this cost effective procedure in identifying children exhibiting behavior disorders. (Author)