This introduction to the theme of political parties presents a wide variety of theoretical approaches - illustrating these ideas by applying comparative approaches to the British case. Political Parties and Party Systems covers all the key subjects of study, including: the classification of party definitions; change in the party system; party institutionalisation; models of party organisation; cohesion and dissent; intra-party conflicts and legislative bargaining; and multi-party electoral competition. Moshe Maor argues that the intra-party arena is the key to the understanding of political party behaviour. Strategic decisions made by party leaders often reflect the internal conflicts with which they are confronted. This study addresses the ways in which intra-party actors solve these trade-offs and in the process how the parties' definitions of activities and motivations are constantly reinterpreted. This is a clear and accessible introduction to modern political science analysis of parties and party systems which will be essential reading for students of politics.