The Theory of Planned Behaviour (TPB) has become a widely used model in environmental psychology, particularly for predicting and influencing pro-environmental behaviours. However, behaviours like waste management, especially in protected areas (PAs), involve complexities that may require an adaptation of this framework. Our paper proposes an adapted TPB framework to identify the factors influencing waste-related behaviours among visitors and staff in Namibian PAs, which are characterised by high tourist flows, remote landscapes, and sensitive ecosystems. Drawing from an extensive literature review, we identify four key constructs, namely awareness, situational factors, perceived moral obligation, and perceived policy effectiveness, as essential additions to the original TPB framework. These adaptations aim to provide a more comprehensive and intricate understanding of waste management behaviour in the context of Namibian PAs. Keywords: Theory of Planned Behaviour (TPB), adapted framework, waste behaviour, protected area, Namibia, pro-environmental behaviour.