The WASA Detector Facility is an internal experiment at the cooler synchrotron (COSY) in Jülich, Germany. The COSY accelerator provides proton and deuteron beams with momenta up to 3.7 GeV/c giving access to hadron physics including the strange quark sector. The physics program with the WASA detector involves hadron dynamics and hadron structure. Key experiments address fundamental symmetries and symmetry violations via the study of rare and not-so-rare meson decays. From the very first production run, results on the Dalitz plot slope parameter in the isospin violating η → 3 π 0 decay have been obtained. The 3 π 0 final state is also used to study meson production mechanisms. Investigations of other decay modes of the η -meson address C, P , and T symmetries and combinations. Higher orders in chiral perturbation theory are probed with the η → π 0 decay. The status and plans for studying hadron structure with Dalitz decays of mesons are presented.