In this chapter the author discusses the idea that a reduced lexicon and restricted set of syntactic structures means that a higher quality of machine translation output can be achieved. The crucial difference between the controlled-language approach of the previous chapter, and the “sublanguage” approach to be discussed in this chapter is that, whereas the restrictions of controlled language are imposed on the authors, those of a sublanguage occur naturally. Like controlled language, a sublanguage approach to MT benefits from the two main characteristics of sublanguage as compared to the whole language, namely the reduced requirement of coverage in the lexicon and grammar. The article looks at the properties of sublanguage, more specifically the lexicon, syntax, text-type, and discusses their advantages for MT and CAT systems. A description of Météo, a system to translate weather bulletins from English into French and the classical case of MT that works, rounds off this chapter.