Investment in capacity expansion remains one of the most critical decisions for a manufacturing organisation with global production facilities. Multiple factors need to be considered making the decision process very complicated. The purpose of this paper is to establish the state-of-the-art in multi-factor models for capacity expansion in manufacturing plants and networks. A three phase research programme is presented consisting of an extensive literature review and a structured assessment of the strengths and weaknesses of the current research. The study found that there is a substantial amount of work on development of mathematical multi-factor models for capacity expansion. Despite that, no single work captures all the different facets of the problem.