The validity of the multiple-choice Sequential Tests of Educational Progress (STEP) Writing Test (1957) was tested by the University of Chicago Center for the Cooperative Study of Instruction. Seven criteria developed by the center to score essay assignments were used to determine the relationship between STEP and actual writing behavior. Of the four objectives of the STEP test which appeared congruent with four of the essay-grading criteria, a comparison of scores showed a small significant correlation between STEP and the "Punctuation" score, a moderate significant correlation between STEP and the "Usage" and "Effective Organization of the Paragraph" scores, and no significant correlation with the "Sense of Audience and Purpose" score. The analysis indicated that (1) the ability to produce good writing appears only moderately related to the ability to manipulate previously given material on STEP, and (2) the total writing score from STEP does not relate strongly to any of the individual essay-evaluating criteria but does agree moderately with their combined score. The results must be qualified, however, since no measures of parallel form or score reliability were available. (LH)