Engineering schools across the country are developing ways of integrating design into their curriculum, and a question that often arises is how to best integrate design into the sophomore and junior level courses. Freshman design projects or mechanical dissection courses are designed to give the students hands-on experience in conceptual design and construction, with little if any of the mathematical modeling normally used in engineering design. The capstone senior design project is a true engineering design experience, where students draw from their background to conceptualize, analyze, model, refine, and optimize a product to meet design, manufacturing, and life cycle cost requirements. The sophomore and junior level courses should assist students in making the transition from the "seat-of-the-pants" freshman design approach to the engineering design approach required for the capstone experience and engineering practice. This paper summarizes a three year effort at integrating design into the Mechanics of Materials course, but the principal conclusions drawn would apply to most sophomore and junior engineering science courses.