A few full scale field tests were conducted on instrumented steel sheet piles under vibro-driving to find out the characteristics of the dynamic behavior of a sheet pile. These sheet piles were tested for situations with and without clutch friction. Parameters of the proposed vibratory pile driving model were correlated with the blow count (N-value) of the standard penetration test obtained from the test site. By comparing the peak amplitude of the section forces at the sheet pile heads for situations with and without clutch friction, it was found that the peak section forces for a sheet pile with clutch friction were greater than those without clutch friction and also that the distribution of the clutch friction was not constant with penetration depth. The assumption of sheet pile rigidity, which is essential for the proposed vibratory pile driving model, was shown to be justifiable from the test results. The efficiency ratio, which is defined as the ratio between the amplitude of the actual driving force and the theoretical driving force, was derived for all considered depths, and the average value of the efficiency ratios was 0.18. A computer program for the predicting the penetration rate of a sheet pile was developed by incorporating the modified Ramberg-Osgood model, which simulates the dynamic load transfer characteristics of a sheet pile. Both the predicted load transfer characteristics and the predicted penetration rates of a sheet pile agreed well with the measured values obtained from field tests.