The present research provides new insights into the main causes of the unsuccessful negotiation attempts made by the dispute parties in the Nagorno-Karabakh conflict at different points in time throughout the peace talks from 1992 till 2013 and seeks to explain the failure of the sides to achieve a final settlement of the dispute. This research employs a qualitative research design and makes use of the congruence and process tracing methods whereby a time-series comparative analysis of six negotiation phases within the whole Nagorno-Karabakh peace process is undertaken. By studying both the domestic and international context in which the conflict has been embedded, as well as the contents of the proposed peace deals in the past, this study argues that the Nagorno-Karabakh conflict resolution process has failed to produce a final settlement due to the absence of a ripe moment, i.e. a mutually hurting stalemate, and mutually enticing opportunity, a winning formula, the political willingness, the particular quality of the Armenian and Azerbaijani political leaderships, as well as the presence of self-oriented mediators.