Organizational charts of membership structures can be useful tools for monitoring member control when they accurately depict a concept of control grounded in context and theory. This paper develops the concept "member control" by placing it within cooperative principles and democratic theory. From this perspective, members control their organization when, through a democratic process of decision making, they are able to keep the cooperative a cooperative, a condition we call "containment." With this conceptual development, a containment method of member control charting is developed and illustrative examples given.