1. A method to perform an adaptive risk-based assessment of a user attempting participation in an electronic marketplace, the method comprising: assigning a risk assessment process associated with the user; using a plurality of assessment factors in the risk assessment process; determining whether to allow the user to perform an action in the electronic marketplace based on a response of the user to the plurality of assessment factors; performing a post-action analysis of the risk assessment process; and based upon a result of the post-action analysis, modifying the risk assessment process.