There seems to be a limitless demand for human talent, making well-educated people transfer between countries. Research on such international talent flows has traditionally featured organizational expatriates (OEs), who have been assigned and supported by their parent organizations in relocating to a foreign host country. But international assignments have become increasingly complex. Recent developments in international assignments have seen individuals who personally take charge of their careers without the direct involvement of any organization. These expatriates, who themselves make the decision to live and work abroad, have been called self-initiated expatriates (SIEs). For those expatriates, the initiative for leaving the home country comes from the individual, and the move is not supported by any current employer. The literature on SIEs is rapidly emerging but demonstrates a considerable extent of conceptual confusion. That is not only unfortunate, but may have a negative impact on the attempts to increase our knowledge about this important and growing group of internationally mobile individuals. Therefore, the purpose of this chapter is to enhance the conceptual coherence of the notion of an SIE by proposing a definition based on a set of conceptual criteria which differentiates SIEs from other types of international movers. Additionally, the chapter will feature recent research on SIEs including their adjustment, performance, personality, demographic characteristics, and reasons to expatriate as well as an agenda of future research on self-initiated expatriates.