Modern yield monitors consist of arrays of electronic sensors, in-cab display, and other hardware, all integrated and attached to the harvester to monitor the instantaneous flow of harvested material (i.e. grain, cotton fiber, etc.) as it is being picked in the field. Internal algorithms convert these signals into units of crop yield. Additional instrumentation like GPS makes possible to record and analyze the distribution of yield values in the field. Most often, yield maps show the variation in yield across the entire field, which in Arizona can easily reach 50% in CV (coefficient of variation). Yield monitors provide an information loop that Growers and Crop Consultants can use as feedback when measuring the response of the crop to the production inputs used during the growing season, and therefore adjust their management strategies. Moreover, these data provide an excellent framework to develop site-specific management programs of fertilizer, water, and other inputs. Commercially available cotton yield monitors rely on microwave energy (John Deere) and optical (AgLeader and Agriplan) sensors to measure the flow rate of seed cotton through the ducts of the machine. In this presentation we will focus on the factory-installed yield monitor system of Case I-H cotton harvesters, specifically we will describe setup instructions and calibration procedures for the AFS-Pro-600 system used in a 6-row Cotton Express 620 machine in Central Arizona. A brief description of data export into AMS farm management software is included. At the time of this webinar the latest version of AFS display is the Pro-700. Although there are some differences in software architecture, the operational and functional aspects of these displays are similar.