Which European country was the first to legalize same-sex marriage?

The Netherlands was the first country to legalize same-sex marriage.

Dutch legislation opened civil marriage to same-sex couples on 1 April 2001. Parliament approved the bill in 2000: the House of Representatives voted 109–33 on 12 September, and the Senate approved it 49–26 on 19 December. Queen Beatrix gave royal assent on 21 December 2000.

On the law’s first day, four same-sex couples married in Amsterdam. The reform also addressed adoption rights, making the Dutch law more comprehensive than arrangements that merely recognized partnerships or offered limited legal benefits. The Netherlands had already introduced registered partnerships in 1998, but those were distinct from marriage.

Canada, Spain, and Belgium were early adopters, which can cause confusion. Canada became the first country outside Europe to legalize same-sex marriage nationwide in 2005; Belgium did so in 2003, and Spain followed in 2005. The Netherlands therefore remains the canonical answer for the first country worldwide.