First, more institutionalized party systems enjoy considerable stability; patterns of party competition manifest regularity. A system in which major parties regularly appear and then disappear or become minor parties is weakly institutionalized, as is one in which parties' vote totals often fluctuate widely.
Second, more institutionalized systems are ones in which parties have strong roots in society. The ties that bind parties and citizens are firmer; otherwise, parties do not structure political preferences over time and there is limited regularity in how people vote. Strong party roots in society help provide the regularity that institutionalization [End Page 69] implies. Similarly, links between organized interests and parties are generally more developed, although even in institutionalized systems there are considerable variations along this dimension.
Partly as a consequence of these links, parties in more institutionalized systems tend to be consistent in their relative ideological positions. A party that is markedly to the left of another party does not suddenly move to its rival's right simply to gain short-term electoral advantage, for parties are constrained by their need to maintain the support of activists. If major parties change their relative ideological position, it usually signals weak ties between parties and society and a lack of regularity in the process of how parties compete and how they relate to social actors.
Third, in more institutionalized systems, the major political actors accord legitimacy to parties. Elites and the citizenry in general believe in parties as fundamental, necessary, and desirable institutions of democratic politics. Legitimacy is a dimension of institutionalization because the latter concept implies that actors base their behavior on the expectation that a practice will continue. Legitimacy reinforces the tendency of actors to expect and to perpetuate a pattern of behavior.
Finally, in more institutionalized systems, party organizations matter. Parties are not subordinated to the interests of a few ambitious leaders, but possess an independent status and value of their own. Institutionalization is limited as long as a party is the personal instrument of a leader or a small coterie. As institutionalization grows, parties become autonomous vis-'a-vis individuals who initially may have created them as mere instruments. It is a sign of greater system institutionalization if parties have firmly established structures; if they are territorially comprehensive; if they are well organized; if they have clearly defined internal structures and procedures; and if they have resources of their own. In more institutionalized systems, there is a routinization of intraparty procedures, including procedures for selecting and changing the party leadership.