ASQ-3, which includes 21 questionnaires, covers 1 month through 5½ years of age. The following intervals are available: 2, 4, 6, 8, 9, 10, 12, 14, 16, 18, 20, 22, 24, 27, 30, 33, 36, 42, 48, 54, and 60 months of age.