RESUMEN
Multisyllabic decoding poses a significant challenge to upper elementary grade readers. The purposes of this study were to (a) examine the reliability and validity of a classroom assessment, the Multisyllabic Decoding Inventory (MDI); (b) describe fourth- and fifth-grade students' decoding of multisyllabic words in relation to their semantic difficulty (age of acquisition ratings); (c) investigate which aspects of word knowledge (word recognition and decoding skill, vocabulary knowledge, and morphological knowledge) predict real word and nonword reading for multisyllabic words; and (d) determine how student word knowledge and semantic difficulty of words jointly affect the odds of accurately recognizing a multisyllabic word. We found that (a) the MDI demonstrated acceptable internal consistency reliability and concurrent validity with standardized measures of word recognition and oral reading fluency; (b) students demonstrated strong performance in reading multisyllabic words and nonwords, but words with higher age of acquisition were less frequently recognized; (c) multisyllabic word reading was predicted by word recognition and decoding skill, vocabulary knowledge, and morphological knowledge, whereas multisyllabic nonword reading was predicted by decoding skills and morphological knowledge only; and (d) grade level, word recognition and decoding skill, and vocabulary at the student level increased the odds of recognizing a multisyllabic word correctly, whereas a word's age of acquisition rating decreased the odds of recognizing a multisyllabic word correctly. The results suggest that students in the upper elementary grades may benefit from multisyllabic decoding instruction that integrates decoding and vocabulary strategies.