Almost 250 years ago, 'gang-masters' - those who mediated between rural employers and roving bands of migrant workers - were vividly brought to life within the pages of Marx's Capital. By contrast the modern-day phenomenon of how paid-for labour market intermediaries - temporary staffing agencies and their rural 'gangmaster' counterparts - construct transnational workforces remains remarkably undocumented, let alone theorised. Similarly, although a burgeoning literature sheds light on the increasing privatisation of international migration flows, the precise role of profit-seeking 'recruiters' within a broader migration industry remains underexposed. This thesis explores how - and why - agencies recruited migrant workers from his or her home countries and placed them in temporary employment in the UK. In response to the apparent growing significance of temporary staffing agencies in facilitating migration into the UK from the EU8 countries of Central and Eastern Europe, as well as from beyond the EU, the research was funded by an ESRC CASE studentship. Evidence was gathered from qualitative interviews conducted with representatives of agencies in the UK, in Poland, the Philippines, and Australia, as well as with a range of respondents from government departments, labour organisations, regulatory bodies, and journalists in all four countries. The multi-scale fieldwork sites were selected in order to offer a comparative analysis of variable institutional and regulatory settings. Within the following pages I argue that agencies in both the origin countries, as well as in the UK, made markets in the recruitment and supply of temporary migrant workers; selling migration to recruits, and migrant workers to client employers in the process. Activities of agencies were highly embedded within the precise institutional and regulatory regime that resulted from the interaction between that in place in the origin country as well as that in the UK. The thesis seeks to contribute empirically and conceptually to a growing literature which exposes the behaviour of temporary staffing agencies within national labour markets as well as the migration industry literature which looks at the behaviour of actors which transport workers between national labour markets.