The 26 classroom observation systems in this anthology were primarily designed to collect data about pupil and teacher behaviors for use in research, teacher training, and supervision. The particular aspect of interaction measured by any one of these instruments reflects the interest of its author, but are generally classifiable as cognitive or affective. Systems measuring the cognitive domain code such verbal behaviors as giving data, asking for data, clarifying, defining, giving opinions. Other cognitive systems provide methods for analyzing sequences of statements to determine underlying though processes such as data recall, data processing, and evaluation. Systems dealing with the affective domain assess the affective climate of the classroom and how it is conditioned by teacher reactions to pupils' feelings, ideas, work efforts, or actions. Abstracted from articles by each system's author, descriptions in the anthology include data collection methods, purposes and implications, observer reliability procedures, and categories used in coding behavior. Included are a 369-item bibliography and an abstract for each of the following instruments: Amidon System, Amidon-Hunter System, Aschner-Gallager System, Bellack System, Flanders System, Gallagher System, Honigman System, Hough System, Hughes System, Joyce System, Lindvall System, Medley System, Miller System, Moskowitz System, Oliver-Shaver System, Openshaw-Cyphert System, Simon-Agazarian System, Smith System (Logic), Smith System System (Strategies), Spaulding System (CASES), Spaulding System (STARS), Taba System, Withall System, Wright System, Wright-Proctor System. (DL)