T H E G L O B A L S TAT E O F C I T I Z E N S H I P Executive summary basis of their sex, gender, or sexual orientation. Examples of direct discrimination in citizenship laws are when only fathers (and not mothers) can pass their nationality to their children, when only men can transfer their citizenship to their female spouses, and where heterosexual couples can transfer citizenship to their partners while same-sex couples cannot. Such overt discrimination is on the decline because of the growth of international human rights norms on sex/ gender equality. Even so, new forms of discrimination are evolving in the context of the increasing accessibility to alternative reproductive technologies and the growth of diverse families. No matter where or to whom we are born, we all have the right to be recognised as a citizen of at least one state in the world. This is what is meant by Article 15 of the Universal Declaration of Human Rights, which states that ‘everyone has the right to a nationality’. Even so, we live in a world where over four million people are stateless, because their citizenship remains denied or unrecognised. Living up to the promise of eradicating statelessness is challenging because each state decides on how its citizenship can be acquired and lost. In this report, we map the variety of ways in which states regulate citizenship. In so doing, we identify the obstacles that individuals face in being recognised as citizens that arise from different and uncoordinated approaches of states around the world. Immigrant inclusion Most immigrants can only obtain the citizenship of their new country by applying to be recognised as citizens after living in the country for a certain amount of time. Such ‘ordinary naturalisation’ comes with the challenge of recognising the effective ties and interests that bind immigrants to their new adopted home. The kinds of links you are required to prove as a prospective citizen differs greatly between countries. In some countries, these requirements, such as ‘good character’, are based on what most citizens of a country have in common. In others, naturalisation requirements such as income and integration, indicate that in their quest for the ‘perfect citizen’, states expect more of immigrants than what they expect of their own citizens. Most people acquire citizenship on the basis of birth; this is the so-called birthright citizenship. People obtain birthright citizenship either by having one or both parents who are already citizens of a country, or by being born on the country’s territory. For states, these are not mutually exclusive ways to grant birthright citizenship; in fact, most states around the world use both. For instance, if a country grants citizenship based on birth on its territory, it may still grant citizenship to children of its citizens born abroad. Equally, a country that grants citizenship to children of its nationals may recognise nationality to foundlings or children who would otherwise remain stateless. Citizenship laws not only shape immigrants’ opportunity to become citizens of their new country; they also shape public attitudes and immigrants’ wider socio-economic opportunities and sense of belonging. The legal requirements for ordinary naturalisation are most inclusive in traditional migrant destination countries in the Americas and Western Europe. They are uneven in Africa and South and Southeast Asia, and most restrictive in Central and Eastern Europe, East Asia, the Middle East and Oceania. While some people are struggling to be recognised as citizens, others may have the right to more than one nationality. Having more than one nationality is often due to a family history of migration, marriage, cultural belonging, or talent. Historically, dual or multiple citizenship was not accepted because it raised concerns over loyalty. Over the last decades, the acceptance of dual citizenship has been on the rise. For instance, in 1960, only six percent of the world’s countries accepted dual citizenship. By 2024, this increased to 51%. Worldwide, the most common ordinary naturalisation requirements are five to seven years of legal residence, a good character or no criminal background, and a basic level of language knowledge. Less common requirements include economic self-sufficiency, civic or cultural integration or assimilation, specific language or citizenship tests, and renunciation of any foreign citizenship. Adopting a more restrictive approach to naturalisation is directly reflected in how many immigrants succeed in becoming citizens. Gender equality Everyone should have equal access to citizenship, regardless of their sex, gender, or sexual orientation. Equal access should be an undisputed norm. However, citizenship laws around the world reveal that discrimination on these grounds persists, either directly or indirectly. Direct discrimination in citizenship law takes place when a person is unable to acquire or transmit citizenship on the 1