The Canadian Cohousing Network considers the following to be essential features that define cohousing:

Residents participate in the planning and design of the development of the community so that it directly responds to their needs. (Developer initiated/driven projects are in no way a threat to this. In most cases, developer initiation may actually make it easier for more people to participate in the process. On the other hand, a well-designed, pedestrian-oriented community with no resident involvement in the planning might be “cohousing inspired”, but is not a cohousing community.)
The physical design encourages a sense of community as well as maintaining the option for privacy. (It is harder to define here exactly what constitutes “encouraging a sense of community,” but rather than saying it must be a pedestrian-oriented design with the cars at the periphery, it is more important that residents are involved in the decision making (see above) and the intent must be to create a “strong sense of community” with design as one of the facilitators. Getting together to afford your private golf club does not do it.)
Common facilities are designed for daily use; they are an integral part of the community and typically include a dining area, sitting area, children’s play room, guest room, as well as garden and other amenities. Each household owns a private residence —complete with kitchen-but also shares extensive common facilities with the larger group. (Cohousing is not a shared house. A shared house could be included in a cohousing community but is a different community/housing type.)
After move-in.
There are leadership roles, but not leaders. The community is not dependent on any one person, even though there is often a “burning soul” that gets the community off the ground, and another that pulls together the financing, and another that makes sure you, the group, has babysitters for meetings, and another… (If your community has a leader that sets policy or establishes standards unilaterally, it is not cohousing.) The community is not a primary income source for residents. There is no shared community (communal) economy. (If the community provides residents with their primary income, this is a significant change to the dynamic between neighbors and defines another level of community beyond the scope of cohousing.) by Kathryn McCamant and Charles Durrett 3rd North American Cohousing Conference Seattle, September 1997