The central idea of this textbook is to use multiscale methods to derive modelings for various materials in mechanics of continuous media with structure definitions ranging from angstroms to millimeters. This is a book for students in engineering and hence the models are not rigorously derived but only carefully defined, described and illustrated by various application examples, mainly drawn from the thermodynamical properties of crystalline solids. The book comprises four parts: continuum mechanics and thermodynamics, atomistics, atomistic foundations of continuum concepts, and multiscale methods. A large number of topics are considered; more specifically, the book, loosely speaking, combines thermodynamics, quantum mechanics of materials, molecular statics, molecular dynamics, and multiscale modeling.