There are a number of reasons for the declining party membership numbers in New Zealand – all of which generally fall into two broad categories: (1) reduced supply of members from civil society, and (2) reduced demand for members by the parties. Supply-side arguments revolve around changes in society, such as lifestyle and declining political preferences that make membership less relevant or appealing to citizens. Demand-side arguments are related to changes in the organisation of the parties, and in particular, the shift to the electoral-professional model which has less of a demand for citizen involvement because of a reliance on party professionals and the almost pure focus on elections and the media. The following blog posts will elaborate, first on supply-side explanations, then on demand-side explanations.