As SMEs transformation to sustainable practices in manufacturing, processing and services, is declared to be the key to a green growth model, the research in this thesis aims to understand in what way eco-labelling can be a part of that. In order to approach this complex issue, the thesis aims to identify the greening potential and the limits of contemporary eco-labelling schemes for SME product within the German coffee-processing sector. With regard to that, the thesis applied the policy evaluation method "Program Theory Evaluation" (PTE), which assesses a policy in place and thus provides information how the introduction and the function of eco-labelling schemes is observed and perceived by German coffee-processing SMEs (GCPS). Hence, based on a policy evaluation from a rational perspective, which has the focus on the policy’s problem-solving process and implementation cycle, the thesis reveals how eco-labelling schemes’ underlying theoretical greening strategy act in practice to German coffee-processing SME (GCPS). Thereby it could be evaluated that eco-labelling schemes imply shortcomings to address and green GCPS high quality coffee products. As the PTE-method aims also on optimizing the policy’s rationalisation, the inappropriate or failed implementation of eco-labelling schemes by GCPS has been further explored. To grasp the eco-labelling schemes extent of limits to green GCPS products, the thesis compares and analyses the policy evaluation results against the backdrop of eco-labelling schemes’ normative theoretical policy conception and in the light of "Environmental Authority of Political Consumerism (Ecological Modernisation Theory)". With regard to that, the thesis fosters a policy learning process and uncovers that eco-labelling scheme eco-labelling schemes potential to green GCPS products is limited and conditioned to this a lower level of sustainable value as they are focused to supply mainly the demand for mainstream coffee products. Hence, the thesis concludes that it is not the underlying rationality of eco-labelling schemes, namely being a consumer-oriented and market-based policy instrument that does not apply to green GCPS products. However, this opens up a new perspective as it points out a sustainable quality gap between products using eco-labelling schemes and non-labelled GCPS high quality products. In return this raises considerations in terms of improving eco-labelling schemes’ contribution to sustainable development. Thus the thesis argues to optimize their rationalization with regard to GCPS high quality products as frontrunners of tomorrow’s sustainability.