Summary: In 600 words, this entry defines coalition, describes some general attributes of the concept, briefly discusses and contrasts coalitions in different countries, and concludes by addressing the relative stability of coalition governments.
The entry defines a coalition as "several parties pursuing a common goal," and a coalition government as a particular example of the more general concept. Other types of coalitions include the legislative and the electoral. Coalition governments are party governments, and therefore must be distinguished from single-party and non-partisan governments.
Coalitions are rare in pure or modified two-party systems like those in New Zealand, the United Kingdom and Canada. In multiparty systems like Belgium and the Netherlands, on the other hand, almost all governments are coalitions. Such coalition governments generally contain between two and five parties. In rare cases, a 'grand coalition' will form, which is a government composed of all parliamentary parties. More typically is the 'minimal winning' coalition, which is a government that includes just enough parties to secure a parliamentary majority.
Power within a coalition government is generally proportional to the relative parliamentary strength of the individual parties. Traditionally, coalition governments are considered less stable than single-party governments. Recent research, however, points to minimal winning coalitions as very stable government forms. In fact, minimal winning coalitions often prove as stable as single-party governments.