The development of a new technique, the Relative Difficulty Ratio (RDR), is described, as well as how it can be used to determine the difficulty level of a test so that meaningful inter-test difficulty comparisons can be made. Assumptions made in computing RDR include: 1) each item must be scored dichotomously with only one answer choice keyed as correct; and 2) all wrong responses are a result of guessing. RDR has an upper limit of 1.00 for both a test and an item when all examinees have a perfect test or item score. The lower limit is reached when all examinees miss all items. The RDR not only facilitates comparisons between tests (i.e., multiple choice and true-false), but also can be useful in judging the adequacy of the difficulty level of a single test. As RDR decreases from zero, the interpretation is that the test is more difficult than is desirable. The opposite interpretation should be made when the RDR approaches its upper bound from zero. (RL)