Expatriation is a big topic, and getting bigger. Over 200 million people worldwide now live and work in a country other than their country of origin. Tens of billions of dollars are spent annually by organizations that move expatriates around the world. Yet, despite the substantial costs involved, expatriation frequently results in an unsatisfactory return on investment (ROI), with little or no knowledge as to how to improve it. Why is this so? The problem overwhelmingly lies in the poor delivery of effective expatriate management which is frequently handicapped by a lack of understanding of international careers and the forces that drive competition in the 'global war for talent', an increasingly short-term profit-driven focus, and a failure to adopt the rational strategic approach that organizations automatically apply to other areas of their business. Drawing on more than a decade of expertise, research, and publications in top journals, we contend that the key to getting a satisfactory ROI from expatriates is in understanding expatriates themselves, about whose experiences we have extensive information. We provide a practical 'insider's' guide which reveals why expatriates seek and accept international assignments, how they feel impacted by new forms of remuneration and other working conditions, how international assignments fit in with their longer-term career aspirations, and what complications arise in terms of their families. These are considered in a context that includes the understanding of the drivers for mobility in organizations, emerging trends in global staffing, the global war for talent, and alternative strategies to expatriation. We outline for managers and consultants what modern-day global mobility is like (based on our decade-long study with nearly four hundred expatriates and their managers, over a hundred of whom we interviewed personally), how it is changing, and why now, more than ever, a hard-nosed ROI approach is necessary. By drawing on our extensive experience and research, observations of key trends, and 'crystal ball' predictions, we define new practices for managing global mobility and consider forecasted trends in expatriation over the next decade.