We examined the technical adequacy of writing progress measures as indicators of success on state standards tests. Tenth-grade students wrote for 10 min, marking their samples at 3, 5, and 7 min. Samples were scored for words written, words spelled correctly, and correct and correct minus incorrect word sequences. The number of correct minus incorrect word sequences written in 7 and 10 min yielded the highest reliability and validity coefficients. Tables of Probable Success were created to illustrate the relation between scores on the progress measures and the state tests. Exploratory analyses of differences in correlations between English Language Learners (ELL) and non-ELL students revealed a similar pattern of results for the 2 groups, but correlations were stronger for ELL students than for non-ELL students.