At the beginning of the twentieth century, Ferdinand de Saussure had developed a new theory of language. He considered natural language as a structure of mutually linked elements, similar or opposed to each other. Later, several directions arose in general linguistics and many of them adhered to the same basic ideas about language. This common method was called structuralism, and the corresponding scientific research (not only in linguistics, but also in other sciences belonging to the humanities) was called structuralist.
Between the 1920’s and the 1950’s, several structuralist schools were working in parallel. Most of them worked in Europe, and European structuralism kept a significant affinity to the research of the previous periods in its terminology and approaches.
Meantime, American structuralists, Leonard Bloomfield among them, made claims for a fully “objective” description of natural languages, with special attention to superficially observable facts. The order of words in a sentence was considered the main tool to become aware of word grouping and sentence structures. At this period, almost every feature of English seemed to confirm this postulate. The sentences under investigation were split into the so-called immediate constituents, or phrases, then these constituents were in their turn split into subconstituents, etc., down to single words. Such a method of syntactic structuring was called the phrase structure, or constituency, approach.