The design and development of a test of inference ability in reading comprehension for grades 6, 7, and 8 (the Phillips-Patterson Test of Inference Ability in Reading Comprehension) are described. After development of a contemporary theoretical framework for the test of inference ability in reading comprehension, the design, item development, and test development iterations of the test are outlined. The test was administered to 999 students from schools in Alberta, Newfoundland, Labrador, Nova Scotia, and Ontario, Canada. Test score results were analyzed by province, sex, grade, and age group. Data analysis provided results on item difficulty, the relationship of item performance to overall performance and of story performance to overall performance, test wiseness, guessing, and Kuder-Richardson 20 Reliability Indices. A copy of the test is appended. (TJH)