Charcoal fragments occur frequently in the light fraction (LF) and this suggests that charcoal C is an important constituent of LF of North American soils. Charcoal is highly resistant to biological degradation, hence it will have significant implications for studies of LF composition, dynamics and modeling exercises. This study aimed to quantify the contribution of charcoal to free LF (density £ 1.8 g cm^-3) C, and its effect on the turnover of C in that fraction using the d¹³C technique. Duplicate free LF samples were obtained from the 0-20 cm depth of tilled and no-tilled soils, each under long-term corn and tobacco/rye cropping. Based on morphological properties, charcoal and plant fragments were handpicked from one set of free LF samples and their d¹³C were measured. The d¹³C of whole free LF samples were also measured. A two end-member mixing model was used to estimate the proportion of free LF C derived from C₃ and C₄ plants and charcoal in continuous corn plots. The chemical properties of charcoal fragments, as determined using solid-state ¹³C NMR spectroscopy, were consistent with charcoal and d¹³C (26 to –25 ‰) showed that charcoal C was derived entirely from C₃ vegetation. Charcoal- and previous C₃ residue-C accounted for between 72 to 75% and 25 to 28%, respectively, of the total C₃-C in the free LF, indicating that charcoal C was responsible for the persistence of a sizable portion of native C in free LF. The turnover of C₃-C in free LF without charcoal was faster (8.3 to 9.5 yrs) than that of free LF containing charcoal (21 to 23 yrs), indicating that C₃-C derived from charcoal slowed the turnover of C₃-C in free LF by 2.5 times. These results provide supporting evidence that charcoal C is likely to lead to misinterpretation of dynamics of the LF.