Introduction
Social barriers are barriers to entry which are created by the culture of the community, i.e. people's behavior towards newcomers or others in general.
Behavioral norms
For example, rudeness, arrogance and unrealistic demands towards newcomers can be seen as social barriers, and they definity raise the bar for new contributors.
Governance and transparency
David Neary makes a good point in his barriers to entry checklist about importance of good governance and transparency. You should take a look at his good arguments - I'll add some of mine here.
Now, the method of governance depends highly on the type of your project. Some software projects are very strongly vendor-led, whereas others purely community-driven. Taking down social barriers related to governance and transparency in a community-driven project is fairly straightforward:
- All important decisions should be reached through a public discussion. The idea is to allow everybody to participate in the decision making process and to ensure transparency of governance. Decisions made behind closed doors give the impression that community's feedback is not valued, which can be seen as a sign of disrespect or even arrogance ("we're not interested in your opinions").
- All community members should be held to the same standards. Double standards can be created easily by mistake, e.g. by granting new employees commit access to the project's VCS repository on the first day while at the same time requiring community developers to prove themselves worthy through a long process. From a community member viewpoint a person's "employee status" is completely irrelevant to the project, and should not carry with it any extra privileges. Also, these privilege grants are by their nature closed-door, one-sided decisions which should be avoided.
In vendor-led projects things are more complicated. If the project is vendor-led because of necessity, having truly open governance might not help much. For example, if your business is based on an open core business model, trying to setup open governance makes little sense: there's an inherent conflict of interest between you and the community. This will render any open governance efforts if not entirely useless, at least much less effective.
On the other hand, a project can be vendor-led because of practical barriers to entry. In this case removing as many of those barriers could make the project more community-driven.