An overview of several available methods for prediction of the transition location is presented. Two particular methods are discussed – the eN method, and the empirical, correlation-based, model of Langtry & Menter (2009). The role of stability theory is explored, including local stability theory, incorporation of non-parallel effects (parabolized stability equations), and extensions into the nonlinear regime. Limitations and drawbacks are pointed out and possible future paths for improvement are highlighted. An area of particular interest is the receptivity stage, where environmental disturbances and surface imperfections trigger instability mechanisms in boundary layers.