Challenges in Mechanics of Time—Dependent Materials, Volume 2 of the Proceedings of the 2019 SEM Annual Conference& Exposition on Experimental and Applied Mechanics, the second volume of six 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 Conditions & Environmental Effects Soft Materials and Biomaterials Damage, Fatigue and Fracture Structure, Function and Performance Rate Effects in Elastomers Viscoelasticity & Viscoplasticity Research in Progress In—situ Techniques and Microscale Effects on Mechanical Behavior Fracture and Fatigue in Brittle Materials Novel Experimental Methods Fatigue and Fracture in Extreme Environments Integration of Models and Experiments Failure in Elastomers and Gels Rate Effects in Elastomers Microscale and Microstructural Effects on Mechanical Behavior Mechanics of Energy Materials Additive Manufacturing: Fatigue and Fracture Mechanics of Composite Materials Interfacial and Mixed—Mode Fracture Vibration Effects and High Cycle Fatigue