The objective of this project is to quantify the age-dependent material properties of porcine brain tissue and to correlate them with structural alterations associated with growth and development. Samples of frontal cortex from neonatal (2-3 days) and adult pigs were harvested and tested within 3 hours post-mortem. The complex shear modulus of the samples was measured in a custom-designed oscillatory shear testing device. Samples were tested at a shear strain amplitude of 2.5% from 20-200 Hz at 25°C and 100% humidity. The elastic and viscous components of the complex shear modulus change significantly with the development of the cortical region of the brain. These changes in material properties correlate with increases in myelin, brain mass, total cell number, and a decrease in water content. This project is the first step in developing head injury tolerance criteria for the infant and young child.