The citation style you choose will largely be dictated by the discipline in which you're writing. For many assignments your instructor will suggest or require a certain style. If you're not sure which one to use, it's always best to check with your instructor or, if you are submitting a manuscript, the publisher to see if they require a certain style. In many cases, you may not be required to use any particular style as long as you pick one and use it consistently. If you have some flexibility, use the guide below to help you decide.
When in doubt, try: Chicago Notes
See also: Additional Citation Styles, for styles used by specific engineering associations.
If you’re enrolled in classes that each require a different citation style, it can get confusing really fast! The tools on the Quick Citation Generators section can help you format citations quickly in many different styles.