Between 1999 and 2009 the Swedish Armed Forces underwent an immense reformation. This thesis aims to contribute to the discussion on small state foreign policy behaviour within the wider field of international relations by explaining why Sweden decided to reform their national defence from an invasion-based defence to a mission-based defence. Using a neoclassical realist approach and a process tracing methodology, two hypotheses are tested to analyze a predicted causal relationship between systemic imperatives, the search for influence, and the decision to reform the Armed Forces. The first hypothesis is that when a state’s relative power rises it will initially seek, but ultimately attempt to gain, more influence abroad. The second hypothesis is that the search for influence is the driving force behind the reformation of the Armed Forces. The analysis corroborates both hypotheses, although the former with a relative amount of uncertainty, and argues that both system and intervening unit-level variables matter. The main conclusion is that the favourable situation in the international system has permitted an increased search for influence. This search for influence has in turn been the driving force behind the reformation. Since the first hypothesis has a relative amount of uncertainty connected to it, the certainty of the conclusions in this thesis can be discussed, and must therefore be subject to further empirical research.