Most computer series have their own distinct operating system control language. At present there is no world-wide standard control language, but the recent development of heterogeneous networks, where users may access many different computers, has highlighted the need for one. A project to set up an experimental network, called KIWINET, between Massey and Victoria Universities, initiated research into the design of a standard control language for the network. The result of this research is a high-level, block structured language called the Network Command Language (NCL). The design of this language and its implementation are discussed.