Marine plastic pollution (MPP) is one of the most pressing issues especially for fast-growing economies in the Global South where addressing it involves both government and personal actions to achieve effective waste management policies. Alternative modelling strategies accounting for personal traits and beliefs (latent attitudes) which are unobservable characteristics are frequently overlooked in policy assessment studies. This study combines contingent valuation and latent traits questions to derive the willingness of Indonesian respondents to support MPP mitigation initiatives. One and two-step models are compared to test the sensitivity of results to modelling assumptions. Latent traits help to understand the willingness to pay (WTP) for MPP and one and two-step approaches produce comparable results. On average respondents are willing to pay £15, per person, per year to reduce MPP, or 2% of the average monthly salary. Local and international organizations should consider motivations and latent traits when designing MPP mitigation strategies.