The unprecedented demand for child care throughout the world, coupled with increased funding for child care services and facilities in northern Europe and North America, presents a major challenge for theoreticians, researchers, and designers of children's environments. No comprehensive source of up-to-date information exists on the design of child care centers. The Children's Environments Research Group in New York City, USA, and its journal, Children's Environments Quarterly, do an admirable job of trying to make information available. The Center for Architecture and Urban Planning Research receives numerous requests from designers around the USA and overseas. The importance of the designed environment in child care is slowly being recognized. Research now indicates, for instance, that aggressive and destructive behavior increases and social interaction decreases when children are restricted to too little space (about 2 m2 per child). Elizabeth Prescott at Pacific Oaks College in Pasadena, California, USA, found that center size was one of the most reliable predictors of program quality -- very large centers rarely offer children the same range of experiences found in smaller and medium sized centers (45 to 75 children). And the US National Day Care Study of 1979 determined that the size of the group in which the child spends the most time makes a great difference in influencing quality child care. The design disciplines in North America and Europe have responded by creating developmentally appropriate child care centers. There are several exemplary facilities around the US, including the Harold E. Jones Child Care Center in Berkeley designed by Joseph Esherick & Associates and the, United Community Day Care Center in Brooklyn designed by Robert Mangurian/Works East. In Europe a number of innovative centers exist, and have been well published in the European architectural press, including buildings by leading architects like Herman Hertzberger in the Netherlands, Ralph Erskine in Sweden, Reirna Pietela in Finland, and a range of younger designers in France, Germany, and Italy. In 1978 my colleagues and I were asked to develop a set of national guidelines for the design of child care centers. As part of this multi-year, multi-disciplinary project, we evaluated 52 centers and playgrounds around the USA, interviewed experts in design and developmental psychology, and critically reviewed all research evidence and design publications (over 2,000 articles and books). The result was the creation of 115 design patterns for child care centers and another 75 for associated play yards. The work was disseminated in the late 1970s and 1980s in a seven-volume series of reports. Two reports - Case Studies and Recommendations for Child Care Centers -- received recognition for design research in the annual Progressive Architecture awards program. Since that time, we have visited and evaluated another 84 innovative child care facilities throughout Europe, looking especially at those which have been premiated in the European architectural press in order to evaluate the current relevance of those patters, to revise many in the light of current thinking in different European countries, and to create new patterns that fit specific sociocultural contexts. This paper will be based on work conducted over the past two years in Europe and the US. The focus of the paper will be on the mutual relations between child /environment theory (Piagetian based interactional-constructivist theory), empirical research and post-occupancy evaluation, and research-based design applications. The theme will be how the form of the architecture of child care has been transformed under the socio-historical contexts of different European countries. Examples will be drawn primarily from Europe. Illustrations will include sketches,and design solutions by architects from Europe and North America, supplemented by case study material from my current design consulting work, e.g., a 2050 m2 child care center with Schroeder Piwoni Architects for Northern Michigan University and an 1800 m2 center with Shaughnessy Fickel and Scott Architects for the Saint Joseph Health Center in Kansas City.