There are no gaps between age intervals for ASQ-3 and ASQ:SE-2 questionnaires so there is always a questionnaire available for children in the appropriate age ranges (1-66 months for ASQ-3 and 1-72 months for ASQ:SE-2). Even when there is not an ASQ:SE-2 questionnaire with the exact same age as an ASQ-3 questionnaire, there is still an ASQ:SE-2 questionnaire appropriate for the child's age. For an 8-month-old child, the ASQ-3 8 month and ASQ:SE-2 6 month would be used. The administration window for each questionnaire is listed on the cover sheet. For easy questionnaire interval selection, you can use the online calculator or the free ASQ calculator apps in the Apple and Google Play stores.