This paper presents an investigation of the time development of dynamic and static elastic moduli of eight mortars made using CEM I cements with contrasting properties. Mixing and the preparation of dynamic testing prism specimens conformed to European standards. A nonstandard specimen and bending test setup was devised for measuring the development of a static Young's modulus. It was determined that dynamic Young's moduli determined using an ultrasonic pulse velocity test are often, but not always, greater than those determined using a resonant frequency test. The ratio of a static Young's modulus to a dynamic Young's modulus for a particular cement mortar increased nearly linearly with increasing static modulus after 3 days, and this increase can be predicted using the measured 3-day static modulus. In addition, methods for predicting the increase in the static and dynamic modulus and decrease in Poisson's ratio of mortars, from age 3 to 56 days, using measured 3-day elastic moduli, are presented. Predicted 56-day values of static Young's modulus, dynamic modulus, the ratio of these, and Poisson's ratio for the eight different mortars were within 5% of the measured values. The observed relations among different elastic properties may be useful for verification of prediction models. (C) 2014 American Society of Civil Engineers.