CDU/CSU

CDU/CSU, unofficially the Union parties (German: Unionsparteien, pronounced [uˈni̯oːnspaʁˈtaɪ̯ən]) or the Union, is a centre-right Christian democratic political alliance of two political parties in Germany: the Christian Democratic Union of Germany (CDU) and the Christian Social Union in Bavaria (CSU).

The CSU contests elections only in Bavaria, while the CDU operates in the other 15 states of Germany. The CSU also reflects the particular concerns of the largely rural, Catholic south. While the two Christian Democratic parties are commonly described as sister parties, they have shared a common parliamentary group, the CDU/CSU Parliamentary Group, in the German Bundestag (German: CDU/CSU-Fraktion im Deutschen Bundestag) since the foundation of the Federal Republic of Germany in 1949. According to German Federal Electoral Law, members of a parliamentary group which share the same basic political aims must not compete with one another in any federal state.

The parties themselves officially remain completely independent with their own leadership and only few issue- or age-based joint organisations, which makes the alliance informal. However, in practice the committees of the parties harmonise their decisions with each other and the two parties run behind a common candidate for Chancellor, and the leader of one party is usually invited to party conventions of the other party.

Both the CDU and CSU are members of the European People's Party and the International Democrat Union. Both parties sit in the European People's Party group in the European Parliament. The CDU and CSU share a common youth organisation, the Youth Union, a common pupil organisation, the Pupil Union of Germany, a common student organisation, the Association of Christian Democratic Students and a common Mittelstand organisation, the Mittelstand and Business association.