Risk assessment has become increasingly important as a tool in assessing risks from food-borne pathogens. There are many methodologies that may be used when constructing a risk assessment model, and there are many methodological issues, which are left to the risk assessor’s choice. A number of different approaches to developing a risk assessment model are detailed in this chapter, including the use of deterministic and stochastic variables. A step-by-step approach to creating a quantitative risk assessment model is given. The approach is illustrated with a worked example focusing on potential human exposure to bovine spongiform encephalopathy via meat products. A general framework and guiding principles for constructing a quantitative risk assessment are given, in addition to an outline of the use of Monte Carlo simulation, event tree/fault tree analysis, and sensitivity analysis. This chapter presents a procedure that will enable readers to familiarize themselves with the risk assessment process and equip them with the procedures necessary to construct risk assessment models for food-borne pathogens.