Objective: To compare patching and atropine as treatments for moderate amblyopia in children younger than 7 years. Methods: In a randomized clinical trial, 419 children younger than 7 years with amblyopia and visual acuity in the range of 20/40 to 20/100 were assigned to receive either patching or atropine at 47 clinical sites. Main Outcome Measure: Visual acuity in the amblyopic eye and sound eye after 6 months. Results: Visual acuity in the amblyopic eye improved in both groups (improvement from baseline to 6 months was 3.16 lines in the patching group and 2.84 lines in the atropine group). Improvement was initially faster in the patching group, but after 6 months, the difference in visual acuity between treatment groups was small and clinically inconsequential (mean difference at 6 months, 0.034 logMAR units; 95% confidence interval, 0.005-0.064 logMAR units). The 6-month acuity was 20/30 or better in the amblyopic eye and/or improved from baseline by 3 or more lines in 79% of the patching group and 74% of the atropine group. Both treatments were well tolerated, although atropine had a slightly higher degree of acceptability on a parental questionnaire. More patients in the atropine group than in the patching group had reduced acuity in the sound eye at 6 months, but this did not persist with further follow-up. Conclusion: Atropine and patching produce improvement of similar magnitude, and both are appropriate modalities for the initial treatment of moderate amblyopia in children aged 3 to less than 7 years.