This course is intended as a bridge between introductory-to-intermediate materials science knowledge and mechanical behavior of various crystalline and amorphous systems (Junior or senior year students could find it beneficial). It covers the influence of microstructure on the mechanical behavior of materials including metallic alloys, polymers and ceramics. The main objective of the course is to describe the ways in which microstructure and defects are exploited to fabricate high-performance materials that are applied to today's technologies ranging from aerospace to toughened ceramics. The content includes and is not limitied to stress-strain relations, elastic and plastic deformation, dislocations, dislocation interactions, work hardening, vacancies, interaction of precipitates with defects, glass transition in polymers, creep in materials, brittle fracture and ductile fracture, case studies that span a wide variety of phenomena including fatigue in alloys.