Anxiety disorders are characterised by distorted beliefs about the dangerousness of certain situations and/or internal stimuli. Why do such beliefs persist? Six processes (safety-seeking behaviours, attentional deployment, spontaneous imagery, emotional reasoning, memory processes and the nature of the threat representation) that could maintain anxiety-related negative beliefs are outlined and their empirical status is reviewed. Ways in which knowledge about maintenance processes has been used to develop focussed cognitive therapy programmes are described and evaluations of the effectiveness of such programmes are summarized. Finally, ways of identifying the effective ingredients in cognitive therapy programmes are discussed.