In this collection we have presented research across various themes – the politics of borders; the law; social care; mental health; media and representation – to try and better understand the circumstances of unaccompanied asylum-seeking children as they enter, and progress through, what ought to be a system of care and protection.

The work in this collection has had two key driving factors: first, its interdisciplinary approach; and second, its focus on social justice and human rights. In terms of its interdisciplinarity, this collection builds on the ‘Uncertain Journeys: Exploring the challenges facing separated children seeking asylum’ seminar series that the co-editors ran in 2013–16. The Uncertain Journeys events allowed for a wealth of interaction between those who, though working on very similar issues (such as legal protection; social care; psychotherapy), had not necessarily encountered the research findings of each other's specialised fields.

Some examples of cross-disciplinary insights have been for instance:

• • The problematising in Chapter One of the notion of ‘border’ as a singular, fixed entity, and exploring its many and often conflicting iterations – border as defined by geographical feature, by nation states, by international treaty – enhances subsequent discussions of legal issues (Chapter Two) and the international case studies (Section 3). A range of actors, including unaccompanied young migrants themselves, are involved in both recreating and challenging borders through their actions. Thus the work of legal professionals, social workers, psychotherapists, media reporters and NGO volunteers is implicated in working with and reinforcing existing borders, or seeking to transform or remove them (see Crawley and Skleparis, 2018, on migrant categorisations).

• • Work around identity and belonging, by Sue Clayton (Chapter Four) and Gillian Hughes (Chapter Five) has been helpful to those working in social care.

• • Issues discussed by Gillian Hughes, and by Lousie Drammeh (Chapter Six), inflect questions to do with young people's behaviour in the courts and giving evidence.

• • Insights about the complexities of age assessments (Anna Gupta, Chapter Three), and the ethical and professional dilemmas that conducting these imposes on social workers, have been brought to the attention of the legal and policy making sector.

• • The book creates a better understanding of the UK system within the wider perspective of other state regimes; as described in Chapters Eight, Nine and Ten, and of a rapidly-changing world order, as we discuss in Chapter One.