• Handbook Index
• Improving Your Writing Style
• Stages of the Writing Process
• Common Writing Assignments
• Grammar and Punctuation
• • Using Dashes
  • Using Commas
  • Using Semicolons
  • Using Coordinating Conjunctions
  • Using Conjunctive Adverbs
  • Subject-Verb Agreement
  • How to Proofread
  • Twelve Common Errors: An Editing Checklist
  • Clear, Concise Sentences
• Cite References in Your Paper
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9. Comma splices

Do not link two independent clauses with a comma (unless you also use a coordinating conjunction: and, or, but, for, nor, so, yet).

Instead use a period or semicolon, or rewrite the sentence.

Comma splice:

In 1952 Japan's gross national product was one third that of France, by the late 1970s it was larger than the GNPs of France and Britain combined.

Correct:

In 1952 Japan's gross national product was one third that of France. By the late 1970s it was larger than the GNPs of France and Britain combined.

Comma splice:

Diseased coronary arteries are often surgically bypassed, however half of all bypass grafts fail within ten years.

Correct:

Diseased coronary arteries are often surgically bypassed; however, half of all bypass grafts fail within ten years.

For more information on commas see Commas: Punctuating Restrictive and Non-restrictive Modifiers and Punctuating Coordinating Conjunctions and Sentence Adverbs, or take one of the free grammar, style, and style classes offered by the Writing Center.