A study examined the correlations and predictive relationships between reading and language achievement test scores and North Carolina Annual Writing Assessment scores. Subjects, over 1,000 sixth and ninth grade students, were administered both the North Carolina Annual Writing Assessment and the California Achievement Test (CAT) in 1984 and 1985. Results provided interesting information relative to patterns of performance and their relationship to both the prediction equation and the predictors of writing achievement. The results of the writing assessment in 1984 were more positive for sixth graders than for ninth grade students; the reverse took place in 1985. Findings supported the notion that the best predictors of scores on the North Carolina Annual Writing Assessment using the CAT are the Reading Total and Language Total subtests. The low to moderate correlations between the North Carolina Annual Writing Assessment and the CAT evidenced the need for a separate measure of writing. The data also indicated that the predictors of writing performance using a standardized achievement measure varied depending on the difficulty of the composing domain assessed, student preparation, and the resulting distribution of scores. (Extensive tables of statistical data are included.) (JD)