Erect-fruited blackberries are often described as having a wild blackberry flavor. Flavor can be greatly affected by sugar and volatile composition, neither of which is known for erect-fruited blackberries. This study was done to characterize changes in sugar and volatile composition in ripening blackberries. Blackberries of `Navaho', `Arapaho', `Shawnee', and `Choctaw' were harvested at red, mottled, shiny, and dull black ripeness stages. Sucrose was found in small amounts (4% to 15%) in all stages of ripeness in all cultivars. Total sugars increased from ≈20–30 to 60–80 mg/g dry weight as fruit ripened from red to dull black. Fructose and glucose maintained a constant 1:1 ratio with ripeness stage and cultivar. Three of the four cultivars had a linear increase in total sugars with ripening; total sugars increased 4% to 40% as fruit ripened from shiny to dull black. Twenty to 25 volatile peaks were found by headspace gas chromatography in ripening blackberries. Six volatiles, tentatively identified as α-pinene, eugenol, limonene, p-cymene, α-terpinol, and gernaylacetone, appeared in all cultivars, but only in ripe (shiny and dull black) fruit. Few volatile peaks were observed in red (unripe) fruit. Data indicate that blackberries continue to increase in sugars in the latter stages of ripeness and that volatiles unique to ripe blackberries are produced during this period.