Due to the weather variability in Texas, cotton growers are many times faced with a myriad of decisions of what and when a crop management should be used for a specific task. Mainly, these decisions deal with irrigation, defoliation, fertilization, and pest management and are all influenced by weather. Thus, a management program, which consists of several crop simulation models, was designed to aid in agricultural decisions and assist growers to use management practices considering environmental factors. The goal of this work was the validation of a simulation model by comparing measured and simulated values for three years of experimental data obtained with cotton near Plainview, TX. We compared measured and simulated values of canopy development, water use and soil water in irrigated cotton for three years. We conclude that the proposed simulation model is an excellent tool that can assist cotton producers in making management decisions regarding their crop.