Am I required to maintain employment with the same company for all three Co-op semesters?
Not necessarily. However, in order to ensure that you are receiving maximum benefit from your co-op experience and that the key factors for success (described above) are met, it sometimes makes sense that you maintain employment with the same organization throughout your co-op experience. This, in turn, places more responsibility on the faculty advisor to know something about your career goals and abilities, and to help steer you toward a suitable and appropriate co-op experience.
It should be noted, however, that this is not required, and in many instances it is an advantage for you to have co-op experiences with more than one company. Moreover, there is no guarantee that you will be asked to return to the same organization at which you previously worked. This is determined to a large degree on a case-by-case basis.