Field studies were conducted in 2007 and 2008 at Clinton and Faison, NC, toevaluate the influence of Palmer amaranth density on ‘Beauregard’ and‘Covington’ sweetpotato yield and quality and to quantify the influence ofPalmer amaranth on light interception. Palmer amaranth was established at 0,0.5, 1.1, 1.6, 3.3, and 6.5 plants m−1 within the sweetpotato rowand densities were maintained season-long. Jumbo, number (no.) 1, andmarketable sweetpotato yield losses were fit to a rectangular hyperbolamodel, and predicted yield loss ranged from 56 to 94%, 30 to 85%, and 36 to81%, respectively for Palmer amaranth densities of 0.5 to 6.5 plants m−1. Percentage of jumbo, no. 1, and marketable sweetpotatoyield loss displayed a positive linear relationship with Palmer amaranthlight interception as early as 6 to 7 wk after planting (R2 = 0.99, 0.86, and 0.93, respectively). Predicted Palmeramaranth light interception 6 to 7, 10, and 13 to 14 wk after plantingranged from 47 to 68%, 46 to 82%, and 42 to 71%, respectively for Palmeramaranth densities of 0.5 to 6.5 plants m−1. Palmer amaranthheight increased from 177 to 197 cm at densities of 0.5 to 4.1 plants m−1 and decreased from 197 to 188 cm at densities of 4.1 to6.5 plants m−1; plant width (69 to 145 cm) and shoot dry biomass plant−1 (0.2 to 1.1 kg) decreased linearly as densityincreased.