Human actions, motivated by social and economic driving forces, generate various pressures on biodiversity, such as habitat loss and fragmentation, climate change, land use related disturbance patterns, or species invasions that have an impact on biodiversity from the genetic to the ecosystem level. Each of these factors acts at characteristic scales, and the scales of social and economic demands, of environmental pressures, of biodiversity impacts, of scientific analysis, and of governmental responses do not necessarily match. However, management of the living world will be effective only if we understand how problems and solutions change with scale. SCALES (http://www.scales-project.net), a research project lasting for five years from May 2009 to July 2014, was seeking for ways to build the issue of scale into policy and decision-making and biodiversity management. It has greatly advanced our knowledge of how anthropogenic and natural processes interact across scales and affect biodiversity and it has evaluated in a very practical way how this knowledge can be used to improve the scale-sensitivity and effectiveness of policy instruments for conservation and sustainable use of biodiversity. During the project we have especially emphasized approaches that utilize existing biodiversity databases as they are the most widely available information in applied biodiversity conservation. We also tried to integrate the most appropriate assessment tools and policy instruments into a coherent framework to support biodiversity conservation across spatial and temporal scales. While the guidelines, practical solutions and special tools are presented as a special web based portal at a central place, the SCALETOOL (http://scales.ckff.si/scaletool/), the scientific outcome is widely spread over the scientific literature in regional and international journals. With the SCALES book we want to bundle the main results of SCALES in a comprehensive manner and present it in a way that is usable not only for pure scientists but also for people making decisions in administration, management, policy or even business and NGOs; to people who are more interested in the “practical” side of this issue. Yrjö Haila, Tampere