The authors discuss predictions for the pion and kaon interferometry measurements in relativistic heavy ion collisions at SPS and RHIC energies. In particular, they confront relativistic transport model calculations that include explicitly a first-order phase transition from a thermalized quark-gluon plasma to a hadron gas with recent data from the RHIC experiments. They critically examine the HBT-puzzle both from the theoretical as well as from the experimental point of view. Alternative scenarios are briefly explained.