Planar electric metamaterials are experimentally studied in transmission and reflection utilizing terahertz time-domain spectroscopy. Electrically resonant behavior is observed and provides an estimate of the frequency-dependent transmissivity, reflectivity, and absorptivity of metamaterial composites. Numerical simulations are in good agreement with the measured results and provide additional information helpful in understanding their electromagnetic response. Our results and approach help define the boundaries of a metamaterials-based design paradigm and should prove beneficial in future terahertz applications, particularly with respect to novel filtering, modulation, and switching devices. In addition, this work clarifies some of the mechanisms that limit efficient metamaterials operation at higher-frequencies. Copyright © 2007 American Scientific Publishers All rights reserved.