Developmental dislocation of the hip can lead to premature degenerative joint disease, impaired walking, and pain. Surgery is often necessary once these complications have occurred. Hip instability can be treated nonsurgically if it is detected early. Neonatal screening, which has been practiced for almost four decades, is intended to reduce the need for surgery, prevent degenerative joint disease, pain, and mobility limitations. This evidence synthesis focuses on screening and intervention for developmental dysplasia of the hip (DDH) in physiologically normal infants from birth through 6 months. Two systematic reviews of DDH have been published, one by the Canadian Task Force on Preventive Health Care and another by the American Academy of Pediatrics. This evidence synthesis will summarize this previous work with a focus on how methods and conclusions agree and differ, and incorporates published studies since these reviews were completed. DDH represents a spectrum of anatomical abnormalities in which the femoral head and the acetabulum are in improper alignment and/or grow abnormally. The precise definition of DDH is controversial. The spectrum includes hips that are dysplastic, subluxated, dislocatable and dislocated. Clinical instability of the hip is the traditional hallmark of the disorder. In an unstable hip, the femoral head and acetabulum may not have a normal tight, concentric anatomic relationship, which can lead to abnormal growth of the hip joint and may result in permanent disability. Nonspecific instability in the hip is a common finding in newborns. This is particularly true in females, in whom the maternal hormone relaxin may contribute to ligamentous laxity. More than 80% of clinically unstable hips noted at birth have been shown to resolve spontaneously. However, due to the potential for subsequent impairment and the widespread belief that earlier treatment leads to improved outcomes, screening newborns for DDH has become commonplace. Risk factors for the development of DDH include gender, family history of DDH, breech intrauterine positioning, and additional in utero postural deformities. However, the majority of cases of DDH have no identifiable risk factors. The most common methods of screening for DDH involve the physical examination of the hips and lower extremities. Ultrasonography and radiography are also used to screen for DDH. X-ray is less accurate in the first 3-4 months of life, when the bones of the hip are not completely ossified. The use of ultrasonography and/or radiography in screening has been controversial, particularly due to reports of high false positive rates leading to unnecessary and potentially harmful follow-up and intervention. Despite the controversy, ultrasound has been widely incorporated into DDH screening programs in many developed countries. Key Question addressed include: KQ1: Does screening for DDH lead to improved outcomes (including reduced need for surgery and improved functional outcomes such as: gait, physical functioning, activity level, peer relations, family relations, school and occupational performance)? KQ2: Can infants at high risk for DDH be identified, and does this group warrant a different approach to screening than children at average risk? KQ3: Does screening for DDH lead to early identification of children with DDH? 3a: What is the accuracy of clinical examination and ultrasound? 3b: How does the age of the child affect screening parameters? 3c: How does the educational level and training of the screener impact screening? KQ4: What are the adverse effects of screening? KQ5: Does early diagnosis of DDH lead to early intervention, and does early intervention reduce the need for surgery or improve functional outcomes? 5a: Is the likelihood of surgical intervention reduced in children diagnosed at an earlier age? KQ6: What are the adverse effects of early diagnosis and/or intervention? KQ7: What cost-effectiveness issues apply to screening for DDH?