A nonlinear computer program for Freight Car Response Analysis and Test Evaluation (FRATE) has been developed under the sponsorship of the Federal Railroad Administration. The computer program incorporates a model of a Trailer on Flat Car (TOFC) configuration. Validation of the FRATE/T0FC program is being accomplished through comparison of analysis results to the results of vibration tests performed on a TOFC configuration at the Rail Dynamics Laboratory in Pueblo, Colorado. Validation criteria include resonant frequency, deflection shape at resonance and amplification of input motions.This paper presents a brief review of the FRATE/TOFC computer program, a summary of TOFC vibration test results and comparisons of test and analysis results. Procedures followed to achieve acceptable agreement between test and analysis are reviewed.