The maximum performance tests of speech production are those tests that examine the upper limits of performance for selected speech tasks. Among the most commonly used maximum performance tests are the following: maximum duration of phonation, maximum fricative duration, maximum phonation volume, maximum expiratory pressure, fundamental frequency range, maximum sound pressure level, maximum occluding force of the articulators, and diadochokinetic (maximum repetition) rate. Many clinicians use at least some of these tasks as part of an assessment protocol. These tests are analogous to strength, range, or speed tests in clinical neurology. Given the widespread use of these tests and a rather scattered literature on normative values obtained for them, a survey of the data base seemed in order. This paper summarizes the published normative data, discusses the adequacy of these data for clinical application, and recommends interpretive guidelines to enhance the usefulness of maximum performance tests.