To examine fidelity related to how professionals administer and score ASQ questionnaires, some programs do a file review to monitor the screening program. A supervisor checks that a screening was completed, that the correct interval was used, that the questionnaire was scored correctly, that appropriate follow-up action was taken(e.g. conference with parents, referral), etc. You could also create a checklist of steps using the information in the User's Guides.
To ensure fidelity for completing the questionnaires, the ASQ developers recommend that professionals explain to parents the purpose of screening and how to complete ASQ questionnaires; ask parents to complete the items with familiar toys; and encourage them to try the items with their child that they are not sure whether they can do.