An instrument was developed for use in the evaluation of a pilot program to improve the writing skills of elementary school students in the Austin (Texas) Independent School District. Called the "Assessment of Writing Skills" (AWS), the instrument assesses writing maturity, productivity, and writing mechanics by collecting a holistic evaluation and such frequency counts as total words, percentage of words spelled correctly, total sentences, sentence length, total correct punctuations, percentage of correct punctuations, total correct capitalizations, paragraph usage, number of modifying words, and sentence usage. The AWS was used by three raters to evaluate 268 second through fifth grade students' descriptive writing samples during the fall (pretest) and spring (posttest) of the same academic year. A measure of interscorer/intrascorer reliability ensured that the essays were rated consistently. The data reveal that fourth graders had lower pretest scores than third graders on eight of 13 variables, a fact that might be explained by the corresponding shift from printing to cursive writing during that period. The results also suggest that the AWS meets criteria for the evaluation of instructional programs; the holistic scores of AWS can assess overall growth over time, while frequency counts can provide feedback regarding specific skill development and needs for instruction. (RL)