By the end of 1960's, Baka Pygmies have adopted shifting cultivation and have established permanent villages along main roads in close proximity to their farmer neighbors. Their economical and social systems, traditionally based on hunting and gathering and small mobile groups (BAHUCHET 1991), evolved in unprecedented way with crop production and farming. About 25 000 people living in the forest left this habitat to come to live along main roads (DHELLEMMES 1982). While traditional group composition was about 32 persons (BAHUCHET 1992), Baka road settlements is grouping today up to 200 persons. The spatial mobility being considered incompatible with farming and crop production, anthropologists predicted an extraordinary revolution of Baka society similar to the one occurred 10 000 years ago with sendentarization (ALTHABE 1965). This presentation analyzes how and why agriculture adoption was a successful innovation. Using ethnographic data, it shows that innovation was here possible because the change did not lead to the expected revolution or to radical changes. On the contrary, the maintenance of the social organization, and the continuity and the stability of the cultural, political as well as technical systems seem to be prerequisite conditions for successful improvement of traditional production systems. Implication for sustainable development projects is discussed using "social space" as operational concept. Ethnographic survey was lead during two years (1996-1998) using quantitative and qualitative approach to compare Baka Pygmies (N=204) and neighboring farmers (Nzimo, N=200) that are exploiting the same forest and living in the same village. Environment-societies relations were assessed using sociological comparative method: as forest natural resources are available for both Baka and Nzimo, the difference in their techno-economical systems is depending only on cultural factors. The social organization, the spatial mobility, the cropping systems and the area