When writing a research paper or essay in Modern Language Association (MLA) style, source cards can help you stay organized and make preparing your works cited page much easier. If you document each source that you refer to during the writing process, you will also easily be able to identify and return to relevant sources for further study. Although some teachers or professors may ask that source cards be turned in with your draft or final paper, source cards are primarily a tool for the writer and meant to make the writing process flow more smoothly.

On a 3-inch by 5-inch index card, document each source you find that may inform your paper. Because MLA style doesn't prescribe a specific format for source cards, the Research Paper Manual published by the Washington Township Public School District in Sewell, New Jersey, advises that you refer to your assignment guidelines for your teacher's formatting preference.

List all identifying information on your card that will be required on a works cited page. Refer to Purdue's Online Writing Lab to determine specific requirements for citing books, periodicals, electronic sources and other types of references to make sure your source card contains complete citation information.

Include information to help you easily locate the source again in case you need to conduct further research. For example, write the name of the library and the call number, if applicable. This information is for your benefit only and will not be included on your final works cited page.