Despite the apparent effectiveness of cognitive-behavioral therapy (CBT) in the treatment of anxiety disorders, more can be done to predict individual variability in the effectiveness of CBT. One potentially useful predictor involves individual differences in fear inhibition and extinction as similar learning processes are thought to be involved in CBT. Waters and Pine (this issue) present an investigation of the relationship between pretreatment indices of fear extinction and responsiveness to CBT among children with anxiety disorders. We discuss these findings and place them within the context of supporting evidence from neurobiological and genetic research. Various novel ways in which different elements of fear inhibition and extinction can be quantified are then outlined, and the potential utility of this approach for clinicians and researchers particularly in developmental samples is discussed.