This paper examines the life-work histories of twenty four civil society activists that crossed the boundary of the third sector into the government in Mexico 2000-6). The motivation of the study was to document and analyse the experiences of these ‘cross-overs’, since, initial anecdotal evidence suggested that many of these individuals were working on the inside to promote progressive reforms. However, the data collected suggests a far less positive picture. It indicates that (a) some of these people were ill-prepared in terms of their strategy for working within government, both in terms of understanding how things worked inside government, and in having no clear mandate from their constituencies or supporters; (b) some also lacked the necessary skills to negotiate and build agendas and support with other actors within government to shape the policy process once inside; (c) that this made them highly vulnerable to ‘capture’ or immobilisation by interest groups once inside; and (d) that their reputations and relationships with the broader third sector were damaged as a result of their entry into government. By contrast, the evidence suggests that civil society strategies to shape the policy process from outside the government had been more successful in bringing about progressive social change. The paper concludes with reflection on (a) lessons for theorising about civil society and policy change in Mexico and (b) some reflections about civil society and government relationship.