Peter Mair and Ingrid van Biezen, "Party Membership in Twenty European Democracies, 1980-2000," Party Politics, 7 (January 2001), 5-21.

First Paragraph:
This article reports a brief but quite comprehensive overview of new data on the levels of individual membership of political parties in contemporary European democracies. Our first intention here is simply to update the data originally reported in Katz et al. (1992), and to extend their coverage to as many additional European democracies as possible. Our second intention is to assess the extent to which the trend towards declining levels of membership noted by Katz et al. at the end of the 1980s has continued through the 1990s. As that original report concluded, the evidence of membership decline through to the end of the 1980s was in fact uneven, for while the levels were almost consistently falling when measured relative to the size of the overall national electorates (the M/E ratio--total party membership taken as a percentage of the total electorate), this was not always the case when looked at in terms of the raw numbers involved. Thus, while the overall numbers of members in a number of polities had actually remained stable or had even grown in the period from 1960 to the late 1980s, they had usually failed to keep pace with the enormous expansion of electorates in this same period, and hence had registered a relative decline. What we see here now, however, when extending these data through to the end of the 1990s, is not only an accentuation of this decline in membership relative to the electorate, but also, and for the first time, a strong and quite consistent decline in the raw numbers themselves. As we show in this article, in each of the long-established European democracies, without exception, the absolute numbers of members have now fallen, and sometimes quite considerably. What we see here, in other words, is concrete and consistent evidence of widespread disengagement from party politics. In this sense, these data, however crudely aggregated, tell an important story.

Figures and Tables:
Table 1: National levels of party membership in the late 1990s. p. 9
Table 2: Party membership change, 1980-2000: M/E ratios and absolute numbers. p. 12
Table A1: Summary data, by country p. 15- 19

Last Paragraph:
In terms of party membership levels, therefore, and as has already been noted with regard to patterns of electoral participation (Mair, 2000), it is precisely in the 1990s that we now witness the first substantial and consistent aggregate evidence of growing disengagement from conventional politics across western Europe. As the recent literature on values clearly attests, citizens in western Europe appear to be as supportive of the idea of democracy as ever they were. Nowadays, however, they do not appear to be quite so willing to involve themselves in actively maintaining the very institutions which democracy requires if it is to thrive.