Abstract: VTT Technical Research Centre of Finland has done research on different aspects of sustainable building since decades. There\'s a continuous stream of international research projects related with sustainability metrics and building performance, indoor climate and energy efficiency, product development, sustainability assessment and decision support tools. The focus is nowadays increasingly stretched towards sustainable neighbourhoods covering also infrastructure and economic and social assessment. VTT has 50 to 100 experts doing research on sustainable built environment. The number is bigger if the areas of water and waste management, transport, energy systems, etc. are also counted. Based on the wide expertise described, and building on recent experiences carried out in different parts of the world (China, Russia, Finland, Kenya) which can be somehow considered the origin of the new formulation of the concept developed by VTT in line with its Research and Innovation Vision 2020, EcoCities provides a framework for sustainable community and neighbourhood regeneration and development focusing mainly on developing countries and emerging economies. EcoCity Miaoufeng (China), EcoGrad in St. Petersburg (Russia), EcoDrive (Finland) or UN Gigiri in Nairobi (Kenya) are the main references prior to the launch of the EcoCities concept presented in this paper. Among the main challenges addressed by EcoCities are: climate mitigation and adaptation, sustainable urbanization and affordable housing, integrated planning and funding availability, capacity building for local solutions and services, citizen empowerment and participation, crucial cross-cutting themes like gender issues and poverty. To respond to these challenges, EcoCities is built around a strong collaboration with local partners in order to answer to local needs previously identified and discussed with them. The flexibility of EcoCities\' approach allows the implementation of expert solutions depending on local conditions and customized to varying socio-economic realities worldwide. Ongoing projects in Egypt and Zambia, and planned activities in Libya, South Africa or Colombia will illustrate the main components of the concept. Both ongoing New Borg El-Arab EcoCity (Egypt) and EcoLusaka (Zambia) projects have a clear focus on capacity building. Another project currently under negotiation also in Zambia would include the construction of two sustainable demo houses. In South Africa and Colombia, VTT\'s local partners would be the municipalities. All projects within EcoCities framework cover the different aspects of sustainability (environmental, economic and socio-cultural).