This article focuses on the ‘The Constitutive Committee’, the 1971–2 mass-movement to create a general trade union in Bahrain. The first mass-movement after independence, it was also the country’s first public non-sectarian organised movement. Initially a joint effort between ‘The Popular Front’ and the ‘National Liberation Front’, it represented the first formal collaboration between the two major factions of the Left, which had historically entertained an ambivalent relationship. This article traces the committee’s establishment and development, culminating with the ‘March 1972 uprising’. The article places the Constitutive Committee within a historical narrative that begins with the Higher Executive Committee movement of 1954–6 and leads up to the February 2011 Arab uprisings. The framework emphasises the dialectical struggles of popular movements searching for a united front for political change, faced by a regime that has mastered the use of divide and rule to entrench social and political fragmentation.