This document discusses several theories of instructional materials development. It describes instructional design as the systematic development of instruction to ensure quality learning based on analysis of needs and goals. Several theories are covered, including behaviorist theories that focus on reinforcement, cognitive theories like Gagne's conditions of learning, humanist theories emphasizing personal development, and social/situated learning theories involving observation and modeling. Cybernetic theories view learning as involving error detection and feedback. Common instructional design models including the ADDIE model of analysis, design, development, implementation, and evaluation phases and the rapid prototyping and situated instruction models.