The development of effective interventions tackling plastic pollution should consider the human dimension behind the issue. To ensure that solutions are tailored to the Global South, specifically the realities of Small Island Developing States (SIDS), we recommend assessing location-specific behavioural drivers. This study (i) assesses the current behaviours of Trinbagonians related to their use and disposal of plastics, (ii) explores the drivers of behaviour (plastic usage and disposal), policy support and behavioural intentions to reduce plastic consumption and, (iii) makes suggestions in order to foster evidence-based interventions. A co-created online questionnaire designed to collect information from Trinbagonians relating to plastics was conducted over 15 weeks (May to August 2022). We find that the frequency of single-use plastic use was driven by individual and systemic factors, with the latter limiting recycling behaviours. Participants were supportive of policies to reduce plastic pollution and somewhat intended to reduce their own consumption. A complex pattern of socio-psychological, systemic and perception-based factors predicted participants’ behaviour, behavioural intentions and policy support. The present study demonstrates that community perceptions can inform policy-making at two entry points: the consumption and the disposal of plastics. Based on our findings, we also point towards a suite of policy instruments that can be utilized in order foster more sustainable consumption patterns, reduce single-use plastics and promote recycling to reduce recyclables in landfills. Understanding the human dimension of environmental issues is crucial for designing targeted and effective interventions that resonate with specific local realities.