<p>We explored commercial moss picking activities in Mid-Wales (UK). Applying the Socio-Ecological System framework, we analysed the factors affecting the sustainability of this activity. We disentangled how harvesters understood the moss resource and its ecological dynamics, how the value chain functioned and the formal and informal normative framework. Results showed that moss pickers harvested in young conifer stands and had limited formal knowledge of the species picked but apply their observations of how moss responds to picking in constructing practices to ensure their business permanence. This traditional ecological knowledge remains within the enterprises as there is negligible horizontal interaction between pickers. We also noted information asymmetries between pickers and forest managers. This affected the governance system twofold: first, long-term relations and trust were key for managers in reducing field control costs; and secondly, it supported a picking permit procedure that resulted in a rather closed market. In ecological terms, interviewed stakeholders were unconcerned about moss sustainability provided that collection was only of abundant, common species. Hence, there was an apparent socio-environmental-economic equilibrium in the moss-picking sector in Wales. This equilibrium may however become fragile when confronted with scenarios of increased number of pickers or prospective policy restrictions.-</p>