AIM: The aim of this systematic review was to investigate screening practices with the Ages and Stages Questionnaires (ASQ) and the Ages and Stages Questionnaires: Social-Emotional (ASQ:SE) in the USA and Scandinavia and to identify practical lessons and research opportunities.

METHOD: The review was performed for ASQ- and ASQ:SE-related studies in children from birth to 5 years. From nine databases and 1689 references (published from 1988-2018), 127 articles were included and categorized using Covidence online software. The Critical Appraisal Skills Programme Checklists were used before data synthesis.

RESULTS: US studies primarily use the ASQ/ASQ:SE to detect delays in general and at-risk populations in medical settings, which increases early detection, clinician-referral, and intervention rates. Scandinavian studies commonly use the ASQ/ASQ:SE to monitor developmental-behavioural differences in intervention/exposure-based cohorts. Pre-visit screening yields completion/return rates of 83% to more than 90% and fosters same-day interpretation. When referrals are indicated, systemwide care coordination or colocation with a developmental-behavioural specialist is beneficial.

INTERPRETATION: Practical implementation lessons are reviewed. Research opportunities include investigating and measuring the ASQ/ASQ:SE's 'overall' sections. Danish, Norwegian, and Swedish translations are available but up-to-date norming and validation studies are needed throughout Scandinavia. Randomized controlled trials are needed to investigate outcomes in screened versus unscreened cohorts.

WHAT THIS PAPER ADDS: General and at-risk populations broadly benefited from periodic Ages and Stages Questionnaires (ASQ) and/or Ages and Stages Questionnaires: Social-Emotional (ASQ:SE) screening. Pre-visit ASQ and/or ASQ:SE screenining implementation systems work best. The ASQ and ASQ:SE 'overall' sections are not quantifiable and under-researched.