Challenges in Mechanics of Time-Dependent Materials, Volume 2 of the Proceedings of the 2020 SEM Annual Conference& Exposition on Experimental and Applied Mechanics, the second volume of seven from the Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Experimental Mechanics, including papers in the following general technical research areas: Characterization Across Length Scales Extreme Environments & Environmental Effects Soft Materials Damage, fatigue and Fracture Inhomogeneities & Interfaces Viscoelasticity Research in Progress.