Part 1 of this three-part series on integrated care discussed the drivers for change in healthcare delivery in England set out in the NHS Long Term Plan. This second part explores the evolution of mental health services within the wider National Health Service (NHS), and describes important relevant legislation and policy over the past decade, leading up to the 2019 Long Term Plan. We explain the implications of this, including the detail of emerging structures such as integrated care systems (ICSs) and primary care networks (PCNs), and conclude with challenges facing these novel systems. Part 3 will address the practical local implementation of integrated care.