The lithium iron phosphate chemistry is plagued by poor conductivity and slow diffusion in the solid phase. To alleviate these problems, various research groups have adopted different strategies, including decreasing the particle sizes, increasing the carbon content, and adding dopants. In this study, we obtained LiFePO4 powders and/or electrodes from six different sources and used a combined model-experimental approach to compare the performance. Samples ranged from 0.4 to 15% "in situ" carbon. In addition, particle sizes varied by as much as an order of magnitude between samples. The study detailed in this manuscript allows us to provide insight into the relative importance of the conductivity of the samples compared to the particle size, the impact of having a distribution in particle sizes, and ideas for making materials to maximize the power capability of this chemistry. (c) 2005 The Electrochemical Society. All rights reserved.