For microscopic pK a , we find that some transitions are much more consistently predicted than others, but in some cases there is broad disagreement even about the sign of the free energy change associated with a particular transition -so methods disagree as to which protonation state or tautomer is preferred at the reference pH. Participants agreed on the sign of predictions for roughly 56% of all microstates, while 38% disagreed on sign (predictions were negative or positive). Certain chemical transformations were found to have a high level of disagreement, especially protonation of nitrogens in 1,2,3-triazoles, isoxazoles, as well as those in terminal nitrogen groups. Transitions involving keto-enol neutral state tautomerism also often lead to sign disagreement.