Natural history studies have focused on risk for progression in lumbar curves of more than 30 degrees, while smaller curves have little data for guiding treatment. We studied curve progression in de novo degenerative scoliotic curves of no more than 30 degrees. Radiographs of 24 patients (17 women, 7 men; mean age, 68.2 years) followed for up to 14.3 years (mean, 4.85 years) were reviewed. Risk factors studied for curve progression included lumbar lordosis, lateral listhesis of more than 5 mm, sex, age, convexity direction, and position of intercrestal line. Curves averaged 14 degrees at presentation and 22 degrees at latest follow-up and progressed a mean of 2 degrees (SD, 1 degrees) per year. Mean progression was 2.5 degrees per year for patients older than 69 years and 1.5 degrees per year for younger patients. Levoscoliosis progressed 3 degrees per year and dextroscoliosis 1 degrees per year (P<.05). Forty-six percent of patients had lateral listhesis of more than 5 mm at L3 and L4. Curve progression was not linear and might occur rapidly, particularly in women older than 69 with lateral listhesis of more than 5 mm and levoscoliosis. Small curves can progress and therefore should be individualized in the context of other risk factors.