The Auditory Automotive Mechanics Diagnostic Achievement Test assesses an automobile mechanic's ability to determine mechanical faults from auditory cues alone. The 44-item test and its instructions are recorded on magnetic tape; answer choices are presented on tape, and are also written in the printed test booklets. The norming and validity sample consisted of four groups: an inexperienced group of 67 high school students, 91 students who had completed half of a two-year course in automotive mechanics, 67 graduates of that course, and 44 experienced auto mechanics. The reliability was low for the total group, but increased to .738 when eight non-discriminating items were deleted. The validity of the test was shown by differences in the mean scores of the four groups, and by correlations with peer ratings among groups of auto mechanics students. Factor analysis of the test items resulted in three factors that could be interpreted and three other factors. Correlations with other auditory tests were found to be generally low, except for the Tonal Memory Test and the Hidden Tunes Test. A moderate correlation was found with a written achievement test of knowledge of auto mechanics. Descriptions of some standardized tests of auditory-perceptual abilities, compiled in 1957, are appended. (CTM)