This timely Research Handbook brings together 24 chapters with a wide range of different theoretical perspectives, empirical research, and innovative thought provoking ideas relating to an area of organisation and management that has been neglected for many decades - line managers. With a resurgence of interest in the topic in recent decades, this Research Handbook argues that line managers are a critical element of both employee experiences and organisational performance and worthy of close attention. Split into three sections, chapters present various ways in which line managers can implement HRM practices in the organisation, considering the implementation of a variety of HRM policies and practices (content), a variety of implementation processes (process), and a variety of line management actors. It also develops future directions for research on line managers, such as the future of work, digitalisation, robotisation and AI and the gig economy. Integrating theoretical and empirical research, the Research Handbook on Line Managers will be a key resource for scholars in the fields of business leadership, human resource management and organisation studies. It also provides managerial practices for organisations and line managers who are looking to improve the effectiveness and the efficiency of their work.