The Nation4l Congregations Study (NCS) was ";ndUcted in~njunclion~ith the 1998 Ge~ral~~ial Survey (GSS). The 1998 GSS as/ud respondenl8 woo altend religious. s~rvr.ces 10 na~the" rel,lI'ous congregation, thus generating a nationally representative sampk of rel'gwUB congregat'o~.. Data about these congregaRoIUI wen collecud uia a one-hour interuuw with. OM key znformanta ffll1Uster. pru:st. rabbi, or other staff person or kcukrfrom 1236 congregations. Information w~g ather:d aJJ:>utmul~pk aspecl8 of congregations' social composition, structure, activities, and program":,ng: This .artr.c~de8C~S NCS methodology and presen18 sekcted uniuariote resull8 in four.areas: deTlOrmnat,onalttes, sue, politioal activilie.. and worship practices. i Congregations-the relatively small-scale,l~cal collectiviti~s~d Organiz~tions~~d through which people engage in religious activityare a basic umt~f Amencan~h~ous life. They are the primary site of religious ritual activity, they proVIde an orgamzational model followed even by religious groups new to this country, they provide sociability and community for many, they offer opportunities for political action and volu.ntarism: they foster religious identities through education and practice, and they engage m a vanety of community and social service activities (Warner 1994;, Wuthn~w 1991; V~rba et al. .1~~5; Hodgkinson and Weitzman 1992). This list does not exhaust either the kinds of acti'?~es conducted inside congregations or the ways in which cpngregations relate to commumties. Perhaps it is sufficient, however, to make a prima facie case that congregations~a significant organizational population whose internal features and extex:nal re~ations warrant close attention in their own right. Congregations also represent nch SOCIaland organizational~ttings in which a wide array of sociological questions may fruitfully be addressed.. .. Sociologists have, of course, long recognized congregations' significance as an orgamzational population and their potential as a research site. Although the study of congregations as units of analysis began, in the remarkable work of H. Paul Douglass and Edmund deS, Brunner, by combining case studies .with surveys of large numbers of congregations in a variety of denominations (see, for exanlple, Douglass and deS. Brunner