This thesis is dedicated to the topic "multiple use of urban open space". In growing cities open public space is not expanding by itself according to the needs of residents. Therefor governments and urban administrations of growing municipalities are required to provide sufficient open space of a certain quality to meet expected living conditions. The above stated efforts to create additional open urban space are time-consuming and expensive. Consequently, the approach of reserving space for multiple scenarios of city development, a design of open space towards more multifunctional and secure environments of already existing open space is not only possible but reasonable. An additional method to live up to the needs of all urbanites is the here discussed and verified multiple use of yet inaccessible urban open space. Further focus of this thesis is directed to child¿s play and multiple use of open space, plus a historic overview of open space, public, semipublic areas for playing and playgrounds. Children play anywhere anytime but in urban terms they belong to the group of less mobile residents. Children need sufficient qualitative open space especially near their home environment for a healthy development. A therefor conducted pilot project on temporarily opening a semi-open space, the playground area of a Kindergarten in Graz, has been evaluated. Results of the evaluation lead to a realistic discussion about the implementation of such effective multiple use of existing urban open space for children.