The effects of membership in church-related associations and labor unions on age differences in voluntary association affiliations

Purpose: When compositional differences between age groups are controlled, the bivariate, curvilinear pattern of age differences in voluntary association memberships is replaced by one in which peak membership levels occur in late middle age and remain relatively stable thereafter. We sought to determine if this adjusted pattern persists when widespread memberships in two types of associations are removed: (1) church-related organizations, in which membership increases with age but may be confounded with church membership per se; and (2) labor unions, in which membership is also widespread but may not be voluntary. Design and Methods: Total memberships in 14 types of associations were examined using aggregated data from 12 national surveys conducted between 1974 and 1994. Results: The familiar curvilinear relationship at the bivariate level appears, but in the multivariate analysis, membership levels rise from ages 18-24 through 55-59 and persist close to that level through ages 85 and older. Implications: The results reaffirm that age differences in voluntary association affiliations are due to age-based compositional differences; they also show, however, that the pattern observed with controls is neither driven by membership in church-related associations nor altered when membership in labor unions is excluded.