Michigan State University's LearningOnline Network with CAPA (Computer-Assisted Personalized Approach) is building a free open source Learning Content Management and Assessment System. The network, dubbed LON-CAPA, makes online content available cross-institutionally in a shared distributed pool, with a focus in STEM education. It supports content at different granularity levels (fragments, pages, modules, chapters, etc., up to complete courses), and provides tools for instructors to combine these resources into new resources at a higher granularity level. Currently, the resource pool includes material for courses in physics, calculus, chemistry, biology, geology, food science, human medicine, mechanical engineering, and statistics. A gateway to NSF's National STEM Digital Library is under construction. The integrated assessment system offers automatic checking of individualized homework problems, with adaptive feedback available to those who come up with incorrect answers (see http://www.lon-capa.org/).