The purpose of a research project was to find out the barriers to the use of the open entry-exit concept in cooperative vocational programs in the retail clothing area. The researchers developed individualized instructional materials and arranged for them to be accessible to students in 12 secondary and 2 adult programs in Oklahoma City and Tulsa. Efforts were made by researchers and teacher-coordinators to enroll students anytime they wanted to learn about retail clothing between September and December 1977. The open entry-exit concept was implemented in four secondary programs and one adult program. Some of the barriers identified in the nine programs where the concept was not implemented were concerned with the lack of flexibility in the enrollment policies; the lack of an accepted way to establish credit for competency-based achievements of students; and the lack of access to learning materials for students not already enrolled in a cooperative vocational class. The researchers recommended a number of strategies for overcoming barriers to the open entry-exit concept including development of a statewide flexible system of enrollment, initiation of a statewide system for giving credit for competency-based achievements, and/or approval of open entry-exit programs in selected secondary schools in Oklahoma. (Authors/BL)