According to Mancur Olson's free-rider theorem, collective action will neit
her be initiated, nor sustained unless it is found profitable by every sing
le participant. This "n-person prisoners' dilemma" indicates that the succe
ssful cases of co-operation, not the failures, call for an explanation; thi
s is the theoretical starting point for a study of tenant involvement in Sw
edish housing estates. The local histories of 26 housing estates of differe
nt characters and forms of tenure were reconstructed in order to trace the
norms and other social mechanisms behind the sustenance and institutionaliz
ation of collective action. In most of the estates where co-operation had b
een institutionalized the crucial mechanism seemed to have been the develop
ment of norms of local utilitarianism ("I take part if it is needed and I c
an contribute to the collective good."). Go-operation based on this noon te
nds to be representative rather than direct, and the level of activity is c
omparatively low. In some types of estates more contract-like norms of reci
procity ("I take part if others take part.") had also developed. Selective
economic incentives and tenants' self-realization were of less importance i
n upholding co-operation in housing estates. Institutionalization of co-ope
ration was observed in all types of estate, regardless of physical and soci
al characteristics. In the critical consolidation phase, an important role
was played by norms of everyday Kantianism ("I take part regardless of what
others do."). Leisure activities and "estate days", information to tenants
, etc., were important in developing and reproducing a local identity and s
ocial norms of co-operation.