This study investigates Hizb'allah's successful but competing dual development as an extra-institutional Shi'a social movement and an institutional political party. Hizb'allah has traditionally been studied from the perspective of one of its many natures, such as a social movement, Islamic movement, resistance, or political party, each perspective bringing with it limitations and differing interpretations of its identity, motivations, and success. The motivation behind this research was to seek an interpretation of the movement's development and success that would encompass these multiple natures. Through an interpretation of social movement ‘life-cycles', a social movement ‘development model' is proposed that accounts for contradicting theories on the ‘success' of social movements, interpreting success instead as an ability to exhibit simultaneous institutional and extra-institutional natures. The hypothesis provided in this work is that it is an ability to simultaneously exhibit institutional and extra-institutional natures that can be a source of strength and success for a movement, drawing capital from both while avoiding accountability that typically accompanies institutional politics. This challenges traditional theoretical approaches in terms of linear life-cycles with few paths for the social movement to choose from. In turn, questions arise regarding notions of social movement life-cycles being uni-directional, continuously progressing towards ‘institutionalization' or demise. Ideas of an ‘end-date' or ‘inevitable outcome' of social movements are also confronted. This interdisciplinary study is conducted by means of media, archival, and empirical research (participant observation, interviews, and surveys), focusing on changing constituent perceptions of the movement between 1985 and 2013. It is also argued that Hizb'allah's strength is its ability to draw from both extra-institutional and institutional resources while simultaneously avoiding accountability. However, it was also found that, by forming the 2011 governing coalition, the movement upset this balance by subjecting itself to accountability inherent in governance, in turn leading to ‘schizophrenic behaviour' as Hizb'allah sought to serve conflicting constituent and state interests. The significance of this research is that it not only provides an explanation for Hizb'allah's success, but also provides an interpretation of social movement development that accounts for multi-natured movements.