This book traces the evolution of the welfare interests of the child principle over the centuries in England & Wales to provide a record of the key milestones in its development. It does so by comparing and contrasting the part it has played in the public – care, protection and control – and in the private – matrimonial, adoption etc – sectors of family law. By analysing the content of the principle this book discloses the essence of what has been termed ‘the golden thread running through the common law’. By considering the ways in which the legal system has shaped and been shaped by the principle, it reveals its structural influence. By identifying and assessing the significance of its operational role and functions, it shows how this principle has changed the law relating to children. In addition to a digest of cases and legislation that tracks the evolution of this legal principle, academics and other researchers will find a wealth of information on how that evolution reflects the corresponding changes in social mores. For those interested in the ethics and morality, there is much illuminating evidence on how the law has balanced this principle relative to others within both civil and criminal contexts.