Along similar lines, Bolton (1972) talked of “chains of group affiliations” in relation to the structure of overlapping memberships in voluntary organizations. Many empirical investigation have followed, adding details to the broad picture. Diani and Lodi (1988)have documented multiple commitments in Italian environmentalism, with 28 percent of activists being involved in several other environmental organizations, and the same percentage active in both environmental and other political or social groups. Looking at Dutch environmentalism, Kriesi (1993: 186) found 43 percent of core activists to have personal links to other movement activists (25 percent in Italy according to Diani and Lodi), and 67 percent to be connected to other new social movement participants.