This document summarizes a panel discussion on the past, present, and future of inverse modeling and uncertainty quantification in groundwater modeling. [1] Inverse modeling methods have been developed since the 1980s but are not yet standard practice, with only 20-50% of modelers reported to use them. [2] While inverse modeling and uncertainty quantification provide benefits, their use has been limited when not required by regulators. [3] For these methods to see more widespread future application, explicit requirements by regulators may be needed to outweigh concerns about costs and resources required.