Sentence diagramming is a method of showing the structure of a sentence. In the English language, two techniques can be used.

In the more traditional Reed-Kellogg sentence diagram, different grammatical elements are indicated in different ways. For example, an adjective is written on a line diagonally downward from the noun or pronoun it modifies. A variety of ways have been developed to represent structures such as gerunds, noun phrases, and appositives.

An alternative method, called a tree diagram, organizes sentences into a tree-like structure.