Certification of banana plantations is widely used as a device for protecting and improving socio-economic conditions of wageworkers, including their incomes, working conditions and—increasingly—voice [related to labour relations and workplace representation]. However, to date, evidence about the effectiveness of certification in these domains is scarce. We collected detailed field data on (1) economic benefits for improving household income, (2) social benefits for labour practices, and (3) the voice of wageworkers focusing on identity and identification issues amongst wageworkers at Fairtrade certified banana plantations and comparable, non-certified plantations in the Dominican Republic. We used different types of regression models to identify significant relationships. Econometrical analysis of survey results complemented by field observations and outcomes from in-depth stakeholder interviews indicate that the impact of Fairtrade certification on wageworkers’ economic benefits is rather limited. However, the impact on the voice of wageworkers (job satisfaction, sense of ownership, trust), is more evident. On Fairtrade certified plantations workers are more satisfied with the course of life and better represented. Thus while the additional value of Fairtrade certification on primary wages seems limited, Fairtrade has relevant positive effects on the labour force, particularly by delivering in-kind benefits, offering a sense of job-security, improving voice and enabling private savings. Benefits of (Fairtrade) certification, but also other interventions with a similar purpose, might therefore not be discerned in terms of economic benefits such as wages or basic labour conditions that are under direct control of (inter)national law, but they should be identified in terms of social benefits and improved norms of conduct for wageworker engagement.