There are many barriers to optimizing clinical trials in ASD. including biological heterogeneity, limited targets, high placebo response, and uncertainty related to selection of outcome measures. Still, both the pharmaceutical industry and several academic networks are taking several compounds through to phase 2 and phase 3 programs. This panel represents an international public-private collaboration to examine the selection of primary and key secondary outcome measures in several current phase 2/3 programs, explore how such decisions get made and then use emerging data to evaluate how these measures have behaved. The panel will discuss lessons learnt, gaps, and future directions.