This article aims to analyse the factors leading to varying trends in Turkey’s activeness as a mediator in the Middle East during the post-Cold War period. It seeks to investigate which variables – from various levels of analysis – have influenced Turkey’s activeness in mediation initiatives in the Middle East during this period. Moreover, it also aims to explore the relationships between these variables in the scope of which variables come into play in which conditions and, more importantly, which one of them assumes the primary role within this set of interactions. Utilising the theoretical framework of neoclassical realism and international mediation literature, this study specifies an independent variable (security concerns about the neighbouring part of the region), three intervening variables (eagerness of foreign policymakers for diplomatic expansion, domestic institutional constraint, and diplomatic and economic capacity) and finally, a dependent variable (activeness of Turkey as a mediator in the Middle East) to address these questions systematically. By analysing this process through these variables, this article reaches the following two main conclusions: (1) when security concerns increase, activeness decreases. (2) When security concerns decline, the levels of intervening variables determine the degree of activeness.