Civil sector research shows that non-profit voluntary organizations promote egalitarian networks based on cooperation, mutualism and reciprocity, yet studies of the ecology of diverse organizational fields suggest diffuse competitive processes operate in most organizational populations. Organizational ecology models of density-dependent competition in vital rates provide an alternative perspective for examining growth and decline in voluntary organizational populations. However, organizational ecological studies of density-dependent competition are limited to inferring competition rather than validating hypotheses through statistical analysis.

To bridge this gap, I reformulate and extend the organizational ecology framework to determine whether density-dependent competition is a valid explanation of the organizational dynamics among national self-help/mutual-aid organizations. Multivariate analyses of the effects of density-dependent competition on self-help/mutual-aid formation and viability yield the conclusion that density-dependent competition denotes similar processes in market, state and nonprofit organizational sectors.

In brief, competition at the organizational and organizational population levels mediated the influence of population density on founding and disbanding rates. In addition, ecological and environmental factors such as population and organizational -mass (size) and -age were related to vital rates consistent with prior organizational ecology research.