The subject headings are generally prepared upon the assumptions of the cataloguer about the subject of the work. But for creating a proper subject heading, the knowledge about the grammar of subject headings is also necessary. The grammar used in formulating subject headings is not only rules about English words. It is unique in its own way. It is mainly used to avoid ambiguity and maintain uniformity. The knowledge of the grammar of subject headings makes the allotment and creation of subject headings easier for the cataloguer. This article emphasizes on the grammar of subject headings offered by the 20th edition (2010) of Sears List of subject headings. The grammar includes form headings, subdivisions, arrangement order, etc. described with suitable examples. In this article the grammar of subject headings is enhanced by collaborating the technicalities given in the Sears List.