Party membership figures are relevant for membership linkage as the number of members indicates parties’ reach within civil society. Against this background, this chapter examines trends in Nordic political parties’ membership ratios. More specifically, we map variations across countries, among party families, and between old and new parties. Our analysis shows that party membership in the Nordic countries, as in most other parts of the Western world, is in decline. Importantly, however, we find that the Icelandic case stands out and goes against this trend. The analysis also reveals that the decline has been more severe for some groups of parties than others. As expected, parties with roots in traditional economic cleavages have lost quite large shares of their memberships. In contrast, the green and the radical right party families are, on average, on the rise. Similarly, we also found that the big losses of members during the past decades are primarily an effect of a decrease among the old parties, whereas newer parties show an increase.