Abstract: In this paper we report the first lessons learned of an IEP Site experiment realized in the city of Mechelen (Belgium). An IEP Site is a geographically concentrated location where profit, public and social profit organizations join forces to stimulate the inclusive economic participation of vulnerable citizens. Because stimulating inclusive economic participation is one of the basic dimensions of sustainability, an IEP-site can be depicted as the physical residence of a network that supports local sustainability. As Social and Solidarist Economy organizations fulfill a key-role on this location, the IEP Site network can be depicted as a SSE-network. Although the experiment in Mechelen did not correspond entirely with the fundamental features of an IEP Site, the encountered endeavors did generate useful and relevant lessons learned. As such, we have experienced how difficult it is to successfully join forces and to create a well-functioning local network for economic inclusion. Additionally, unexpected setbacks have challenged the partners continuously to come up with creative and on-the-spot solutions. At the same time these setbacks have put their motivation, commitment and resilience repeatedly under pressure. Fortunately, there were also unexpected strokes of luck. Thus, the partners have experienced how a diversified methodological approach and an active participation of vulnerable citizens themselves in the spatial design of the site, has triggered the competences of self-reliance and personal growth of the vulnerable citizens involved. In short, the experiment in Mechelen generates useful new insights that stimulate the further development and successful implementation of the IEP-site concept in Belgium.