The long-term persistence of neurotic symptoms, such as anxiety, poses difficult problems for any psychological theory. An attempt is made to revive the Watson-Mowrer conditioning theory and to avoid the many criticisms directed against it in the past. It is suggested that recent research has produced changes in learning theory that can be used to render this possible. In the first place, the doctrine of equipotentiality has been shown to be wrong, and some such concept as Seligman's “preparedness” is required, that is the notion that certain CS are biologically prepared to be more readily connected with anxiety responses than others. In the second place, the law of extinction has to be amended, and the law of incubation or enhancement added, according to which the exposure of the CS-only may, under certain specified conditions, have the effect of increasing the strength of the CR, rather than reducing it. The major conditions favouring incubation are (1) Pavlovian B conditioning, that is a type of conditioning in which the CR is a drive; (2) a strong UCS, and (3) short exposure of the CS-only.