A sample of 141 Canadian children in grades 3 through 6 wrote to dictation 24 short sentences sampling 90 lexical items representing 10 inflectional morphological categories to study their relation to the written spelling of 40 sight words. The children were encouraged in 3, 30-minute teaching sessions to use multiple strategies of retrieval, sounding out, analogies, and visual verification. The inflectional categories were: possessive singular, possessive plural, third-person singular, plurals involving variant phonetic renderings of /s/, plurals involving stem change, preterite, past participle, contracted form, consonant doubling, and consonant singling. These 10 categories had reasonably high Cronbach's alpha coefficients and were found to be homogeneous by a principal component analysis. A hierarchical multiple regression analysis showed that the inflectional morphology tasks added unique variance (especially for consonant doubling and contracted form) to the spelling of sight words after accounting for age and reading ability. These results were further confirmed for a subgroup of 45 children comprising 14 grade 5 and 6 poor readers, and 14 reading-age and 17 chronological-age control students. Error analyses provided insights into students' use of retrieval and other strategies in their spelling of sight words. (Contains 4 tables and 1 note.)