This chapter reviews joint development practice with particular reference to the spatial definition of joint zones. This experience can be broadly divided into joint zones that have been agreed in addition to a maritime boundary line and those that have been defined in the absence of a boundary line, which have proved a more popular alternative. With respect to the latter type of joint zone, many such joint areas are determined by the limits of competing maritime claims and thus involve the joint development of disputed waters. Some observations drawn from this inventory and assessment of past practice are offered, together with some preliminary considerations on the applicability of these observations to overlapping claims in the South China Sea. Although a number of these cooperative mechanisms predate the United Nations Convention on the Law of the Sea (UNCLOS), such joint maritime zones have predominantly been concluded since the Convention was opened for signature.