A computer based tractor instrumentation system was developed to measure field performance parameters. The system development was divided into three parts: tractor instrumentation, data acquisition, and data analysis systems. Tractor instrumentation was developed by completing the transducer installations on a John Deere farm tractor model 4430H. The data acquisition system was developed by installing a 21XL micrologger, a thermal printer, and a digital tape recorder on the tractor inside the cab. A data analysis system was also developed to retrieve the data from the cassette tape through a C20 interface system and transfer the data to the microcomputer diskette and further to a main frame computer for analysis. The instrumented tractor was tested in the field by conducting a series of experiments under different terrain and operating conditions. Data from these experiments were selected for specific conditions to assist in verification of a previously developed computer model "TERMS". The instrumentation system tested in the field was convenient, simple, and reliable in operation. The instrumented tractor was tested in the field four times without malfunctioning in either data collecting or recording. The data analysis system could dump the data successfully to the main frame computer for analysis.