A longitudinal study determined if children's invented spelling served as a viable predictor of reading achievement and compared the predictive value of assessing children's invented spelling relative to other notable predictors, such as letter names, letter sounds, a concept of a word, and phonemic awareness. Subjects, 52 kindergarten children attending an elementary school representing an upper-middle to upper-class socioeconomic stratum, were given a battery of four beginning reading tasks and a measure of spelling ability twice in the kindergarten year. Two years later, the 38 remaining subjects were given the reading comprehension subtest of the Iowa Test of Basic Skills. Results indicated that letter names and letter sounds continue to be impressive predictors of subsequent reading achievement; assessment of early spelling ability was also a viable predictor even after 16 months. Findings suggest that the critical issue in assessing invented spelling appears to be in waiting until children are capable of producing written language that reflects phonetic processing. (Two tables of data are included; 17 references are attached.) (RS)