This study focused on teacher-education students taking a special-education language-arts course in which information about English word structure was taught. The relationship between students' component reading-related abilities and their performance on three measures of word-structure knowledge, before and after course instruction about word structure, was examined. Students' word reading accuracy and spelling ability, but not their general language abilities or reading speed, influenced their acquisition of word-structure knowledge. Specific patterns of results varied by word-structure task and by time (pre- vs. posttest); however, even students with strong component reading abilities performed at fairly low levels on the word-structure knowledge tasks at pretest, and course instruction influenced students' knowledge acquisition as much as or more than their component abilities did. Findings support the need to provide word-structure information in teacher preparation and suggest that it may sometimes be useful to assess different types of knowledge separately. (Contains 3 tables.)