Writers, practitioners, and researchers have described the basic rules of paragraph writing, and thanks to them, we now know that a standard paragraph consists of a topic sentence, supporting sentences, and a concluding sentence. Although the topic sentence is considered by many to be the most important sentence in a paragraph, since the writer is usually expected to develop a paragraph based on what is stated in the topic sentence, there is limited understanding of what makes a strong topic sentence. By analyzing the existing literature, this paper proposes five basic rules for writing strong topic sentences. Using these five rules and real-world examples, the author demonstrates how written paragraphs can be significantly improved.