Developmental Dysplasia of the Hip (DDH) is a common musculoskeletal condition of infancy, but diagnosis can be delayed. In parts of Australia, after the four-month routine assessment, there is a 16-week interval before the next well-child assessment. This may result in a delay in diagnosing late developing DDH.This case report describes the diagnosis and management of an 18-week old infant with late-onset DDH who was successfully managed with simultaneous Pavlik harnessing with Denis Browne Bar.This case underscores the importance of routine ongoing hip joint screening, inter-professional collaboration of all health care practitioners, and the importance of appropriate training of all practitioners seeing infants, to reduce instances of undetected DDH, reduce medical burden, and prevent otherwise unnecessary surgical intervention.