Description: The results of the Swiss students in PISA 2000 have aroused and alarmed society and education policy makers. As a result, recommendations for different fields of action were published, with the purpose of tackling alleged weak points in the Swiss educational system. One action that is often mentioned is the expansion of institutional after-school care and education ("Day schools" - Tagesschulen, "core-times" - Blockzeiten, day care and after school care programs). One consistent educational policy recommendation is that fulltime programs can provide better support and attention to children's individual strengths and weaknesses. In this way, equal opportunities for children at risk can be raised. There is no research on the effectiveness or the effects of after-school care and education in Switzerland yet. The international situation is similar. There are few studies that focus on the effects of family and out-of-family care related to developmental outcomes of children. Most of these studies are set in the pre-school sector. All together most published studies on presumably high quality pre-school-care programs show positive effects on children's cognitive and social development independently from the families' social background. At the same time, there is a focus on the program's quality. Those few studies focussing on after-school-care programs are mostly evaluations of specific intervention programs in the USA. However the results of these studies and those of the pre-school sector cannot be extended in general or applied without examination to the varying Swiss circumstances. The research project presented in this paper, which is funded by the Swiss National Science Foundation will take place in the German-speaking part of Switzerland and is designed so as to provide empirical evidence and therefore a basis for decisions pertaining to (Swiss) educational policies. This longitudinal study will address questions relating the quality of different settings of institutional (day schools, core-times, after-school programs) and family care to their effects on children's cognitive and socio-emotional development in the first years of school (age 6-8). A specific focus will additionally be on children from families with low socio-economic status. Methodology: The hypotheses will be tested using a longitudinal survey with quasi-experimental design using three testing groups (forms of care and educational settings: core-times, day schools and after-school programs) and one control group. Using a multi-stage sampling procedure regions and communities in German-speaking Switzerland will be selected with a socio-ecological point of view to provide a broad range of predominant conditions given in Switzerland. In the following steps random selection of care and educational institutions providing the three different kinds of after-school care and education will be carried out. This paper will focus on the multi-stage sampling procedure. For gathering information about quality aspects, questionnaires, interviews and observations will be used. To measure quality the German version of the "School-Age Care Environment Rating Scale" (Harms et al. 1996) "HUGS" (Tietze, Rossbach, Stendel & Wellner 2005) will be used. Cognitive and socio-emotional development will be measured by standardised tests, when available. These tests will measure developmental-psychological specificities of primary-school-age children in the different settings. Conclusions: All together it is expected that primary-school-age children with institutional after-school care and education (day schools, core-times, after-school programs) have better developmental outcomes in cognitive and socio-emotional areas compared to children with regular school-education and no specific institutional after-school care (control group). The same effects are expected for children at risk, but to a different extent.