In April 2003, Peru’s cocaleros broke into the national spotlight by mobilising a six thousandstrong March of Sacrifice from their coca-producing valleys to the capital city of Lima. In 2006, cocalero leaders ascended to several political positions at the municipal and national level. However, their political impact has been limited and divisions amongst coca-producing valleys have prevented cocaleros from articulating a unified agenda on the coca issue itself, let alone on wider issues. The experience of Bolivia’s cocaleros presents a very different picture. In 2005, cocalero leader Evo Morales was elected president with the highest margin of victory in the country’s electoral history. He was re-elected in 2009 by a greater margin. Morales and his political party mobilised a broad coalition as they developed an identity of ‘excluded’ that challenged Bolivia’s unrepresentative democracy, neoliberal economic model and relationship with the United States. How do we explain the political ascent of these unprecedented actors that stand on the border of illegality? Why has the empowerment and impact of these actors on their national political landscapes varied so significantly? This work aims to explain the different experiences of the Bolivian and Peruvian cocaleros in gaining political empowerment through contentious action that originated in defence of coca—an issue that is both de-legitimising and divisive. This work presents the political ascent of these actors as cases of identity-formation. It argues that their ability to construct identities that deterred disunity, legitimised their struggle and broadened their appeal determined their degree of political empowerment. Furthermore, it reveals how contentious interactions—bound by the context in which they unfolded—distinctly shaped each case’s identity-formation processes. In Peru, the imposed identity of ‘illegitimate’ weakened the identity of ‘cocalero’ and generated disunity, isolation and a limited political impact. In Bolivia, the identities of ‘syndicalist’ and ‘excluded’ strengthened the identity of ‘cocalero’ and engendered unity, alliance formation and a significant political impact.