Purpose: Esotropia (ET) in infancy may initially manifest as a small-angle, variable-angle, or intermittent deviation. Some patients experience spontaneous resolution and become orthophoric. Others progress to constant large-angle ET and require surgery. The authors examined factors that may be associated with risk for progression to constant large-angle ET.Methods: Seventy-seven infants who initially presented with intermittent, small (/=+3.50 D were treated initially with glasses. Four risk factors were examined: prescription of occlusion therapy, initial visit before 6 months of age, presence of amblyopia, and abnormal stereoacuity.Results: All 12 infants with small or variable angles progressed to constant large-angle ET and surgery. ET resolved spontaneously in 44.6% (29/65) infants in whom it was intermittent. Infants with intermittent ET who received patches as initial treatment and who had abnormal stereoacuity had 3.4x (95% confidence interval [CI], 1.83-6.29) and 3.4x (95% CI, 1.66-6.78) higher risk for progression to constant large-angle ET, respectively. Neither age at initial visit nor amblyopia presented risk for progression.Conclusions: Abnormal stereoacuity and occlusion therapy pose significant risks for progression from intermittent to constant large-angle ET. Intermittent ET that develops during the first year of life has a high likelihood of spontaneous resolution, whereas constant small-angle or variable-angle ET seldom resolves.