The objective of this paper is to explore the dynamics underlying the ongoing expansion of Nairobi city, Kenya. These dynamics could be global and/or local in nature. In the last few years, the Kenyan capital has witness exponential growth. The indicators of this is the rapid conversion of agricultural land around the city into real estate. The coffee estates that traditionally signified the rural character of the peri-urban space has been giving way to symbols of globalization, namely supermarkets and high end middle class estates. In many ways these indicate emerging nature of the metropolis as linked to distant metropolis in other countries rather being defined by nationalism.

There are two forces exacting pressure on the city to expand: forces international in nature (therein globalization is subsumed) as the global economy shifts from west to the east with Africa as the fulcrum of this change. The second force could be a response to these global dynamics namely the implantation of the public policy. Kenya has been implementing the constitutional provision for devolved government. This has seen more resources flowing into the periurban and beyond. This is attracting more economic actors in the neither- nor space between the urban and the countryside. There are malls and roadside markets exhibiting Chinese and European consumer goods. While Nairobi's international linkage is old, it is certainly much younger compared to same experience in North-Africa, something to be explored in this article.

According to the African Bank for Development, "the informal sector contributes about 55 per cent of Sub-Saharan Africa's GDP and 80 per cent of the labour force. Nine in 10 rural and urban workers have informal jobs in Africa and most employees are women and youth." (ABD, 2013). In North American, European Union, and other OECD countries, evidence suggests that the workforce has become flexibilized or informalized. Street trading is a visible side of the so called "informal sector". Despite the huge differences between the "North" and Africa, street trading is growing.

The conflictual usage of space is a pertinent approach that questions the place of street vendors in the city. Space, in the particular case of mobile and precarious street vendors, remains a resource, an object of strategies, of combat and at times a theatre of conflicts. In addition, different types of vendors are also subject to conflict over space: official vendors are opposed to these informal activities that are perceived as disorderly, unsafe and also disloyal competition. On the other hand, competition is strong between vendors, a major reason being limited access to commercial space.

From the example of street trading, the paper presents how a social issue has been addressed as a research question and how the latter has been addressed to the stakeholders. The IFRA-Nairobi (French Institute of Research in Africa) project combined both scientific and practical dimensions, by not only producing and discussing academic knowledge, but also by putting that knowledge at the service of the political debates.

La région de Regueb, au sein du gouvernorat de Sidi Bouzid en Tunisie, a été promue ces dernières décennies comme un pôle agricole national, notamment à travers diverses incitations financières et fiscales aux investissements privés. Ces dispositifs visaient à approvisionner les villes tunisiennes en produits maraîchers, et à rendre le secteur agricole plus compétitif au niveau mondial, afin de participer au développement de l'industrie et du tourisme national. Cette politique a induit une implication croissante de citadins tunisiens dans la région de Regueb à partir des années 1990, et en particulier de certaines élites de la ville de Sfax. Cette communication interroge les relations entretenues aujourd'hui entre ces deux espaces, en identifiant les complémentarités ainsi que les formes de concurrence qui ont émergé entre ces derniers. A partir d'un travail empirique réalisé dans le cadre de mon doctorat, il s'agit de montrer l'influence multiforme des urbains sur l'espace rural de Regueb : flambée des prix fonciers, installations d'exploitations agricoles capitalistes et capitalistiques dirigées par des citadins allochtones, précarisation foncière des paysans, migrations masculines de travail vers les villes et féminisation de la main-d'œuvre agricole. Une grande partie des élites citadines en question contribue à accentuer la concurrence locale sur l'accès aux principales ressources productives (terre, eau, financements agricoles), renforçant ainsi son assise foncière. Ces dynamiques ouvrent des questionnements sur la façon dont les dynamiques socio-économiques à Regueb participent au rayonnement de la ville de Sfax et de ses élites, qui ont historiquement une forte emprise foncière sur leur arrière-pays.