Inclusion criteria for the classification of malingering are shaped and largely predetermined by our explanatory theories. Current theories have postulated the motivation to malinger is either the product of underlying psychopathology (pathogenic model) or criminal backgrounds (DSM III-R model). I have proposed a third model that malingering is typically an adaptive response to adverse circumstances which may best be understood in the context of decision theory. Based on this approach I have argued that indices of malingering should be empirically derived and focused on clinical presentation. Finally, I have proposed a preliminary model for the classification of malingerers which combines clinical data with corroborative evidence.