Reviewed here is global research on how 13 types of Voluntary Membership Associations (MAs) have significantly or substantially had global impacts on human history, societies, and life. Such outcomes have occurred especially in the past 200+ years since the Industrial Revolution circa 1800 CE, and its accompanying Organizational Revolution. Emphasized are longer-term, historical, and societal or multinational impacts of MAs, rather than more micro-level (individual) or meso-level (organizational) outcomes. MAs are distinctively structured, with power coming from the membership, not top-down. The author has characterized MAs as the
dark matter
of the nonprofit/third sector, using an astrophysical metaphor. Astrophysicists have shown that
most
physical matter in the universe is dark in the sense of being unseen, not stars or planets.