Early detection of developmental problems improves outcomes for parents and children. Parents want to be involved in assessment and need high-quality, accurate, and reliable data on child development to help monitor progress and inform decisions on referral. The aim of this paper is to review which websites are readily accessible to parents on child development and to assess their quality. An internet search (on Google and Yahoo) was conducted using the search terms "child development", "parenting", and "developmental milestones". Criteria were agreed for evaluating web-based resources, adapted from and based on previously reported methods. Data were collected on site content, diagrams and layout, readability (Flesch Reading Ease Scale), design, navigability, overall design, and interactive features. Forty-four relevant websites were identified for further analysis: six government, three university, 15 health-care professional, four American Academy of Pediatrics, 10 by journalists, and six undisclosed. The best websites are presented, with justification for their choice. Overall, information available for parents about child development is accurate but much of it is incomplete, unclear, or difficult to access. There is a need to develop an easily accessible, clear, and authoritative resource for parents with illustrations. Focus groups are being held to inform this research further. (Contains 3 tables.)