Quality of the produce is crucial in ensuring fair price to the farmers. Farmers' practices followed in harvesting and post harvesting affects the quality of rubber produced. The present study identified the practices most commonly adopted by cup coagulum producers in different regions of Thailand and its possible effect on quality of the produce. Data were collected through individual interviews with 771 farmers distributed in the historical and new rubber-producing areas. The classification of farmers based on the combination of three practices with a potential adverse impact on rubber quality viz. non-rubber contaminants, latex coagulation process and coagulum maturation, identified the diversity of harvesting and post-harvest practices. Practices were not uniform within regions. However, regional specificities could be highlighted. The main risks for rubber quality were systematic coagulation with sulfuric acid in the Centre-east and North-east and the presence of non-rubber contaminants in the South. Farmers were unaware of the good practices for quality production, the kind of acid that they used, and the impact of their practices on quality. Significant gap exists between the processors' concerns and the farmers' perception of rubber quality. Since the sustainability of smallholders' production largely depends on their ability to meet the quality requirements, interactions between the stakeholders is highly warranted.