ABSTRACT
Legislative party discipline and cohesion are important phenomena in the
study of political systems. Unless assumptions are made that parties are cohe-
sive and act as unified collectivities with reasonably well-defined goals, it is
really difficult, if not impossible, to consider their electoral and legislative
roles usefully. But levels of legislative party cohesiveness are also important
because they provide us with crucial information about how legislatures/
parliaments function and how they interact with executives/governments.
Without cohesive (or disciplined) parties,1 government survival in parliamen-
tary systems is threatened because executive and legislative powers are fused
while in separated systems presidents’ bases of legislative support become less
stable. How do we explain varying levels of legislative party cohesion? The
first part of this article draws on the purposive literature to explore the benefits
and costs to legislators in democratic legislatures of joining and acting collec-
tively and individualistically within political parties. This leads on to a discus-
sion of various conceptual and empirical problems encountered in analysing
intra-party cohesion and discipline in democratic legislatures on plenary
votes. Finally, the article reviews the extant empirical evidence on how a mul-
tiplicity of systemic, party-levels and situational factors supposedly impact
cohesion/discipline levels. The article ends with a discussion of the possibili-
ties and limitations of building comparative models of cohesion/discipline.
