The last few decenniums have seen a flourishing of new sophisticated experimental technique designed to perform experiments on single quantum entities with the aim of gaining new insight in fundamental quantum mechanical phenomena and hopefully resolving some of the paradoxes that regularly pop up in the interpretations [3],[40]. Foremost in these is the problem of dualistic behavior of photons and electrons under delayed choice conditions. The reports in the literature on such experiments are firmly anchored in standard quantum theory and the interpretations proposed are restricted by the causality postulate. In this book we are looking upon these experiments with fresh eyes based on the bitemporal neoclassical theory. According to the foundations of this theory the macroscopic causality does not apply in the domain of microcosm where the experiments on single entities take place. It will be demonstrated that rejection of the causal concept leads to interpretations and resolutions of delayed choice experiments drastically different from the standard interpretations. We shall analyze a few of the most famous and best known delayed choice configurations—the Mach-Zehnder interferometer in this chapter—the EPR experiment in the next chapter.