MID3: Mission Impossible, or Model-Informed, Drug Discovery and Development? At the 2019 ASCPT annual meeting, point-counterpoint discussions were held on key challenges that limit, and future directions that enhance the adoption of MID3 across the drug discovery, development, regulatory and utilization continuum. We envision that the opportunities discussed, and lessons learned from having contrasting perspectives on issues that lack consensus may aid our discipline in more effectively implementing MID3 principles.