The investigation included both industrial and building construction projects. Current practices in using prefabrication, preassembly, and modularization were analyzed in relation to three project issues: forces prompting the use of special construction methods, processes for evaluation and implementation, and project implications. Forces prompting use included adverse site and local area conditions, competitive conditions, specialized building or process technology, demanding schedule, special design requirements, modular design or repetitive units, and potential cost savings. Project implications concerned project feasibility and risk, organization, planning, monitoring, coordination, and results. Guidelines were developed for improving constructability by considering prefabrication, preassembly, and modularization in the early phases of a project. Investigation results demonstrated that construction methods play a fundamental role in defining a project and that special methods allow fabrication and assembly at the most efficient location. Special construction methods also provide options for degree of assembly and level of application. Flexibility and potential benefits change over a project's life cycle, with diverse forces prompting the use of special construction methods. Nonetheless, increased demands on management result from special construction methods, and such methods increase the interdependency of construction operations. Appendixes summarize the findings from specific construction projects. 333 references, 8 tables, and 42 figures