Numerical quantum methods play a central role in chemical research today, with an increasing number of scientific and technological advances relying on model predictions or added theory support. Therefore, it is a general goal of the whole chemistry community to improve the predictive power of such approaches. The DFG Research Training Group 2455 “Benchmark Experiments for Numerical Quantum Chemistry” in Göttingen established a research program aiming to provide landmark experiments for quantum chemical methods benchmarking and to enable such development in a variety of research areas. These include fields traditionally akin to theory, such as gas phase spectroscopy and mass spectrometry, as well as crystal structure determination. However, the push is also to expand into new areas where benchmark data is less common or accessible, such as solution thermochemistry and reactivity at surfaces.