Motivation has been a major research topic within SLA for over four decades, yet has endured a marginalized position within the field, remaining somewhat isolated from its more mainstream linguistic traditions. The analysis of motivation and its role in SLA has largely been at the level of global learning outcomes, and research has had little to say about how motivational factors relate to the interim processes of linguistic development. Thus while motivation is recognized as a prerequisite for successful SLA, the relevance of motivation research to understanding the finer detail of how SLA happens has been unclear. This paper discusses some studies that have attempted to integrate the analysis of motivation with more linguistic approaches in SLA. It proposes an agenda for bridging the gap between motivation and mainstream SLA research, and suggests how motivation research may contribute to the development of major lines of thinking within the field.