To mitigate environmental pollution from a rapidly expanding Thai food processing industry, different options and technologies can be identified. However, actually implementing these environmental improvements within small and medium-sized agro-food companies requires governing efforts of a variety of actors. This paper assesses feasible paths towards the ecological modernization of small and medium-sized agro-food processing industries in Thailand. A so-called quartet-network model is applied to analyze the greening potentials for small and medium-sized enterprises in three agro-food sectors in Northern Thailand: fruit and vegetable processing industries, meat processing companies and fruit wine enterprises. Conclusions are drawn on how actors in the networks around these companies could contribute towards a more sustainable development of these companies. Copyright © 2011 John Wiley & Sons, Ltd and ERP Environment.