The utility of scale model experiments for crashworthiness research is examined. In Part I, two examples illustrate the use of scale models in crashworthiness research. The accuracy of modeling is shown by direct comparison between a model experiment and the test of a complete automobile in high-speed impact. It is concluded that scale models can be used in place of full-scale experiments for many applications. The comparison of hydraulic and plastic deformation energy absorbers in scale model experiments demonstrates the ability of models to reproduce the response of a wide variety of vehicle elements. In Part II, the cost effectiveness of scale modeling is measured by comparing the costs of full-scale experiments with scaled experiments that meet the same objectives. The comparisons include both individual tests of various types and complete vehicle development programs. It is concluded that scaled experiments increase the flexibility, reduce the cost, and hasten the completion of a program.