In what follows we will describe some of the many ideas regarding large groups and problems encountered when attempting to use the large group or a community meeting as a therapeutic tool. We will argue that many of those preconceptions are unnecessarily negative and have led to large groups being under-utilized especially as a therapeutic modality. We will then describe and develop a novel theory of community. This will lead to a set of ideas on the important functions of community as defined herein. We integrate this with Edelson’s theory of social systems (1970). We then outline the components of community based upon the preceding arguments. We argue that the community function as we define it is of vital importance in any socio-therapeutic effort and in the psychological well-being of the individual. We end the section by describing practical ways in which the community function can be enabled, facilitated, and supported. Throughout, we shift back and forth from the terms “large group” and “community.” “Large group” refers to the number of individuals present in the group. Usually a group starts to be considered “large” when it exceeds twelve in number of members, “median” when it reaches about forty-five and 188very large when it approaches about 120 members. “Community,” refers to a function that is either absent or present, to a greater or lesser extent in a group. A further definition of that function is, in part, the purpose of this section.