The study is based on a programme of research into functionintegrated city environments. In-depth case studies have beencarried out on two planning projects in Karlstad andVästerås. The object of these case studies wasexplorative, the intention being to develop a clear idea of theconditions for function integration and how these aremanifested in detailed planning processes. The key concepts of the study pertain to both the localenvironment and the process of detailed planning. Functionintegration is defined as an action within planning. The resultof detailed planning is a physical environment. What theplanning process aims to produce is a function integratedenvironment. The object of study is function integration in theprocess of detailed planning. A function integrated environment needs to be experienced assuch from eye-level. From this perspective it should bepossible to distinguish the following elements in physicalspace in the local environment: residential housing, places ofwork and services, public space with attractive places, publicland which is structured to give the pedestrian a sense ofcontinuity and connection with surrounding areas. The starting-point here is that a function integratedenvironment is one of many local environments. It is a type ofenvironment for which there is ample justification for goodplanning. The contribution of this study to the city planningdebate is primarily empirical. It investigates experiences ofdetailed planning, and conclusions that may be drawn. Onecomprehensive thesis is that in practice, there is a tendencyin detailed planning to separate functions. This is part of theexplanation why planning projects that aim to produce functionintegrated environments can seem overly complex, demanding manyresources. Keywords:Mixed use, detaild development plan, function,integration.