Enlargement of the European Union, with the exception of Greece in 1981, has always taken place in waves. Several countries negotiate in parallel and join at the same time. Indeed, in late 2002 the European Union concluded accession negotiations with a record high of ten countries.
Despite the recurrent tendency to enlarge in waves, empirical studies and theoretical conceptualizations are almost silent on how the various negotiations affect each other. Often accession negotiations are looked upon as a bilateral exercise between, for instance, Sweden and the European Union. This coincides with the EU's official rhetoric, which is repeated again and again in European Council conclusions: applicants are negotiating on their own; the vanguard of the group will not have to wait for the rearguard.
Just from the mantra of international negotiation theory - 'the more the messier' and 'two's company and more's a crowd' - one would imagine that size matters (Midgaard and Underdal 1977; Winham 1977; Zartman 1994). Although multilateral negotiation theory is still rather undeveloped, scholars share the view that the overarching characteristic of multilateral negotiations is complexity. Consequently, scholars focus on how negotiators can limit the complexity to make it manageable for negotiations (Zartmann 1994:3). As a preliminary hypothesis we will therefore expect that the European Union will have a clear interest in linking the various accession negotiation tables together in order to ease the negotiations and hence influence the final outcome.
To be sure, EU accession negotiations are not strictly multilateral. Nor are they classical bilateral negotiations, but rather a mixture of the two. On the one hand, accession negotiations have a clear bilateral dimension, in the sense that the negotiations do not take place around a big table with all candidates present. All applicants travel to Brussels individually and negotiate with the European Union without any other applicant present.
On the other hand, negotiations are also endowed with a multilateral dimension. After all, the European Union has launched a negotiation process with several countries with the aim of reaching one single goal: EU enlargement. Moreover, the negotiations are conducted in parallel.