How can we search for quantum gravity effects?

Since quantum theory and General Relativity are incompatible there should be a new theory which consistently applies to all physical phenomena and in particlar should describe the quantum nature of gravity. This new theory necessarily must lead to effects which are different from effects describable within the present day standard theory. We also address the problem of how to decide whether an anomalous effect to is of quantum gravity origin. We try to classify the possible and expected non-standard effects in order to structure the experimental search for quantum gravity effects and describe the corresponding classes of experiments. One primary classification comes from the principles underlying the present day physics, another classification comes from the structure of present approaches to quantum gravity theories. In both cases, test theories provide a viable scheme for the description of possible deviations from present day standard physics and also help to bridge between statements in some abstract theoretical quantum gravity scheme and a formalism which is more or less directly applicable to the description of experiments. According to that scheme, a survey of the present experimental limits for the validity for present day standard physics or, equivalently, for the search for quantum gravity effects is given. An outlook on possible future experimental developments and capabilites will conclude this presentation.