The aim of this Handbook is to produce an interdisciplinary and international benchmark text for anyone wanting to understand job quality. Job quality matters and has long and continually done so, even if the terminology used to describe it has, and continues, to vary. Debate about the future of work and job quality in the twenty-first century centres on the impact of the new digital technologies of the putative fourth industrial revolution. This debate compounds existing concerns about the restructuring of employment and, importantly, a worrying proliferation of poor-quality jobs, often within the context of neo-liberal political-economic hegemony since the early 1980s or the economic crisis that followed the Global Financial Crisis of the late 2000s. Job quality is offered as a solution to challenges such as health, welfare, productivity, innovation, economic competitiveness, democracy and democratic participation, Bildung cultivation, societal equality, individual andcollective quality of life, and environmental sustainability. As job quality is a key factor in addressing these and the other challenges, it needs to be understood in all its complexity in terms of what it affects as well as what affects it. This Handbook draws together into a single first, an explicit focus on job quality both as a significant factor in and of itself and as producing instrumental effects on a range of other processes and outcomes; second, a catalogue of the diverse range of multiple contributions and applications related to job quality; and third, the complexity and multiple interpretations of the concept of job quality. Each chapter provides distinct responses to the question of why job quality matters, coupled to a contention about for whom or for what job quality matters most. As the chapters with their respective answers and arguments attest, there are a range of ways in which job quality is relevant to an equally broad range of social, economic, andpolitical concerns.