Presented as a mini-course on the design of classroom observation systems, this report stresses the necessity of determining the goals of any study before designing the procedures. Only if the researcher has concretely formulated the questions to be answered, can an observation system be developed that will provide the appropriate data. The importance of a period of preobservation; the choice of an appropriate coding system; and the techniques of data reduction and tabulation are thoroughly discussed. The Solitary Play Coding System, the Teacher Child Dyadic Interaction Coding System, the Texas Teacher Effectiveness Study Coding System, the Junior High School Study Coding System, and the First Grade Reading Coding System are used to illustrate the various complexities of coding systems currently in use. (BW)