Management practices are needed to increase dryland soil C sequestration for C trading to reduce greenhouse gas emission and C fractions to improve soil quality. We evaluated the 21-yr effect of a combination of tillage frequency and cropping intensity [No-till continuous spring wheat (NTCW), spring till continuous spring wheat (STCW), fall and spring till continuous spring wheat (FSTCW), fall and spring till wheat-pea/barley (FSTW-P/B), and spring-till spring wheat-fallow (STW-F)] on soil surface residue C and soil C fractions in 2004 in eastern Montana. Mean annualized straw C returned to the soil from 1984 to 2004 was lower in STW-F than in other treatments. As a result, surface residue C was also lower in STWF than in NTCW and FSTCW. Soil inorganic (SIC) and organic (SOC) C, particulate organic C (POC), and potential C mineralization (PCM) at the 0 to 5 cm depth were higher in NTCW, STCW, and FSTCW than in STW-F. At 5 to 20 cm, SOC and POC were higher in NTCW and STCW than in STW-F, and PCM was higher in STCW and FSTW-P/B than in STW-F. No-tillage increased annualized straw C, SIC, SOC, and PCM at 0 to 5 cm, and POC at 0 to 5 and 5 to 20 cm compared with tillage. Similarly, continuous cropping increased annualized straw C, residue C, SIC at 0 to 5 cm, and SOC, POC, and PCM at 0 to 5 and 5 to 20 cm compared with crop-fallow. Reduced tillage and increased cropping intensity increased dryland C input, C storage in soil and residue, and C fractions that help to increase C sequestration and soil quality.