PLATO IV (Programmed Logic for Automatic Teaching Operations) is the fourth generation of a computer assisted instructional system developed at the University of Illinois. The use of PLATO IV at five community colleges, and an evaluation of its educational impact on participating students, instructors, and colleges are described. The PLATO system was found to be operating essentially as planned by its developers. The system provided a medium for instruction with substantial appeal to both students and instructors, but it had no consistent positive nor negative effects on student achievement nor attrition. The cooperative effort between instructors and developers was successful in that a substantial number of PLATO lessons were designed, developed, and integrated into ongoing community college courses in the five targeted subject areas: accounting, biology, chemistry, English, and mathematics. The usage of PLATO by students and instructors exceeded initial expectations although the extent of usage in classes was somewhat less on the average than had been projected originally. According to the evaluators, the critical factor which accounted for the high acceptance and usage of PLATO was the control that instructors had over its use. The attitude surveys and tabulated results are appended. (Author/GDC)