The seismic testing technique was combined with the maturity concept to monitor and predict the strength gain of portland cement concrete. In this process, the dynamic modulus of elasticity of a given mixture, obtained from its stress wave velocity, can be related to the strength parameters and static modulus of the mixture by using the same specimens used in the calibration process commonly carried out for maturity tests. When these relationships are combined with the maturity parameters, the predictive power is significantly improved. In this investigation, laboratory tests with molded specimens and cores were carried out by the simplified free-free resonant column method, and field tests of concrete slabs were performed with a handheld device called the portable seismic pavement analyzer. On the basis of the results of these experiments, relationships between the dynamic modulus and the strength parameters as well as the maturity are proposed. The technique was shown to be a rapid, simple, and economical means for optimization of concrete mix design, quality control-quality assurance of concrete construction, and determination of the time required before a repaired or newly constructed structure is ready for use.