Though beliefs, ideology, resources and opportunities are important factors, most people will make the final step and participate - and remain active - if their existing social networks overlap. These networks can include friends, colleagues or other SMOs that you already belong to. Diani found that, in Milan, 72% of environmentalists joined via other social networks.
SMOs can either recruit 'blocs' (other SMOs or SMs) or create new blocs
e.g. the gay & lesbian movement in the USA recruited from the New Left and womens' movement
e.g. the Stop the War Coalition in the UK merged the blocs from the SWP, MAB and some Trade Unions to create a large core of the movement
Activists, especially in denser social networks, can develop common identities that become increasingly important with risks, e.g. the freedom summer volunteers. One exception may be with personal transformation, e.g. the Hare Krishna asking for total exclusive membership meaning that social networks couldn't figure.
Networks may develop between SMOs and individual activists because of overlapping membership, the sharing of resources (e.g. the People & Planet network) and to resolve conflicts (especially of ideology and strategy, e.g. the WSF and ESF)