This chapter discusses law on duty of care. Duty is the first element in the ‘negligence equation’ and the primary means of limiting liability in negligence. It begins with the fundamental ‘neighbour principle’ of Donoghue v Stevenson and charts its evolution throughout the 20th century. The current ingredients of the test for determining duty of care in novel situations are: foreseeability; proximity; and fairness, justice, and reasonableness. This is the ‘three-stage’ test set out in Caparo v Dickman (1990), used in novel situations. Policy is a major influence on the development of duty in negligence.