The Questioning Strategies Observation System (QSOS) is designed to record verbal behaviors occurring in the classroom which are associated with the teacher's use of questions. Twenty-four categories are used in three main sections: initiation of the question, response to the question, and reaction to the response. Under initiation, the categories first designate the pupils expected to answer (MDES, mass designated; NDES, no one designated; GDES, group designated, and IDES, individual designated), and secondly identify the question's cognitive level (knowledge, comprehension, application, analysis, synthesis, evaluation, affectivity, and procedure). Two additional types of question are probing and redirecting, intended to elicit additional responses. The response categories are: designated (the response is the expected one), independent (pupils respond without being called on by the teacher), intercepted (a pupil other than the one called on responds), aborted (something interferes to prevent a response), and no response (the question fails to elicit any response). Reaction categories are: approval, acceptance, rejection, criticism, and no evaluation. This version of QSOS was developed for a specific research project and does not include categories for pupil initiated questions or textbook or preframed questions. These will be included in a more fully developed version. (MBM)