A paragraph is a group of connected sentences that develop a single idea about a topic. Each paragraph in your essay should support your thesis and contribute to the overall meaning and effectiveness of your essay. A well-developed paragraph contains:

For a paragraph to develop a single idea, it must have unity: It must stay focused on one idea, without switching or wandering from topic to topic. A paragraph also should be of a reasonable length, neither too short nor too long. Short paragraphs are often underdeveloped; long paragraphs may be difficult for readers to follow. Note that what is an appropriate length may change across genres (or types) of writing — college essays usually have longer paragraphs than newspaper articles, and scholarly articles usually have longer paragraphs than college essays.

Here is a sample paragraph from a college textbook with its parts labeled.

Audiences gather with varying degrees of willingness to hear a speaker. Some are anxious to hear the speaker, and may even have paid a substantial admission price. The “lecture circuit,” for example, is a most lucrative aspect of public life. But whereas some audiences are willing to pay to hear a speaker, others don’t seem to care one way or the other. Otheraudiences need to be persuaded to listen (or at least to sit in the audience). Still otheraudiences gather because they have to. For example, negotiations on a union contract may require members to attend meetings where officers give speeches.

DeVito, The Essential Elements of Public Speaking

Notice also how the writer repeats the words audience(s) and speaker, along with the synonyms lecture and speeches, to help tie the paragraph to the idea in the topic sentence. To visualize the structure of a well-developed paragraph, see Figure 8.1.