Using unique data from a pre-mandatory price-reporting period we empirically investigate the effects of beef packer concentration and size efficiencies, packer procurement and pricing methods, and other market variables and quality characteristics on the prices paid by packers for slaughter cattle. We find that packers pay less for fed cattle in more concentrated regions. However, we find that concentration is only one of numerous market factors determining fed-cattle prices and is less important than many. Quality variables controlled by sellers, such as cattle type, are more important in determining the price paid by packers than packer concentration, size economies, procurement methods, or other variables outside seller control. This analysis then offers a set of hypotheses to consider in analyses of the beef packing industry from the post-mandatory price-reporting period.