Funding sources frequently require a specific initial step in the proposal process: a letter of inquiry. Such a step saves both the funder and the proposal writer time and energy, cutting down on the volume of mail that shuttles back and forth between the two. Funding sources that request a letter of inquiry often specify exactly what kind of information they wish to see in evaluating whether to invite you to submit a longer proposal. Always comply with their guidelines. If they don't indicate a preference, you should provide a scaled-down version of the letter proposal without the headings. Keep it very brief, no longer than one or two pages.