Colloidal assemblies, biopolymer networks, membranes, and many other soft materials present interactions and structural arrangements developed over a broad range of length scales from the nano/microscale for basic constituents to the macroscopic scale for bulk material. This complexity is reflected in their mechanical response at different times and frequencies, resulting in different behaviors at multiple length scales. Measuring and understanding materials' multi-scale mechanical response is of pivotal importance to design and control their final applications, which span the fields of biotechnology, medicine, building materials, food science, 3D printing, and many others. However, this remains a difficult task, and the development of advanced methodologies using experimental, theoretical, and/or computational approaches is required as illustrated in the articles composing this Research Topic.