This brief looks at the potential impact of Brexit on British families in the EU-27, a group that is much less studied than their counterparts in the United Kingdom. As it explores, legal systems are not always designed to cater to the needs of families rather than individuals, and the patchwork of differing rights and benefits for EU citizens and non-EU nationals could mean some family members—third-country nationals, adult dependants, and same-sex or unregistered partners—will fall through the gaps.