Plantation workers have seemingly little opportunities for labour agency, defined as the worker’s ability to act and improve their conditions. In response to a call for a better understanding of the horizontal dimension shaping labour agency, this article questions what local factors determine the worker’s ability to act by analysing the institutional constraints embedded in the national context through a mixed methods approach. A combination of qualitative and quantitative data is used to understand what shapes and constrains the potential for (...) labour agency in the case of plantation workers in the pineapple sector of Costa Rica. We provide new empirical evidence of the relation between the local opportunity structure—proxied by perceived job security and union awareness—and labour agency in terms of a worker’s intention to choose forthright (voice), evasive (exit) or repressed (loyalty) actions. The model results indicate that a lack of job security and a lack of union awareness significantly reduce the likelihood to use forthright actions (such as voicing concerns, striking or joining a union) compared to evasive (such as leaving the job) or repressed actions (such as doing nothing). In addition, the qualitative analysis of the local opportunity structure identifies four institutional constraints: weak employment protection, vulnerability of migrant workers, limited workers’ representation and insufficient labour law enforcement. Besides overcoming these institutional constraints, empowering workers to make their voices heard also requires awareness raising about their collective bargaining rights and more job security. (shrink)