Most empirical case studies on the environment-migration nexus lack theoretical foundation. This chapter gives a short overview on the conceptual frameworks in environment-migration research and proposes a new conceptual approach, “The Capability and Aspirations Approach”. The new approach is inspired by the Sustainable Livelihood Approach (SLA) and Amartya Sen’s concept of capabilities. The chapter explains why development frameworks are suitable to analyse the environment-migration nexus and how the new conceptual approach takes into account the critique on the SLA to ignore intra-household dynamics and non-economic reasons to migrate. Instead it focuses on the capability of individuals to migrate or to stay and their preferences and aspirations, therewith challenging studies that view migration in developing countries as an inevitable consequence of unfavourable living conditions.