Ages & Stages Questionnaires (ASQ) is a flexible system that allows programs to choose the frequency of screening based on what works best with the program’s goals and capabilities. The developers do recommend that programs screen on a regular basis, rather than just once, to detect delays that may develop as children grow. For children birth to 24 months, screening every 4–6 months is adequate. If a child scores in the monitoring zone, programs should rescreen in 2–3 months. For children 2–3 years, every 6 months is adequate unless a delay is suspected. For children 4–5 years, once or twice yearly is usually adequate unless problems are suspected.