The Christian Social Union in Bavaria (German: , CSU) is a Christian democratic and conservative political party in Germany. Having a regionalist identity, the CSU operates only in Bavaria while its larger counterpart, the Christian Democratic Union (CDU), operates in the other fifteen states of Germany. It differs from the CDU by being somewhat more conservative in social matters, following Catholic social teaching. The CSU is considered the de facto successor of the Weimar-era Catholic Bavarian People's Party.
At the federal level, the CSU forms a common faction in the Bundestag with the CDU which is frequently referred to as the Union Faction (die Unionsfraktion) or simply CDU/CSU. The CSU has 45 seats in the Bundestag since the 2021 federal election, making it currently the second smallest of the seven parties represented. The CSU is a member of the European People's Party and the International Democrat Union.
Party leader Markus Söder serves as Minister-Preside