The validity of cut-off scores, used to place students into English and mathematics courses, and a dichotomized success variable, representing student abilities related to success in three sequential mathematics courses, were investigated. This study, examining the cutting scores of students entering Mercer County Community College in Fall, 1978, on the state-mandated New Jersey College Basic Skills Placement Test, identified the success variable in a three course algebra sequence as an earned grade of C or above. Because the success variable for each course yielded the minimum ability required for success in that course, the raw score equivalent in each case was interpreted as a cut-off score. The Rasch model was used to link student success in a course with a particular ability on the latent trait. Items were calibrated using the BICAL program and adjusted. Results suggested that the abilities required for success in the three courses were extremely close to one another. Content and grading practices of the three course sequence should thus be redesigned. (RL)