Despite the rapid proliferation of technological adjuncts in cognitive behavior therapy (CBT), much of this development appears to have occurred on an ad hoc basis and in many cases has resulted in applications that are beyond the resources of most practicing clinicians. The authors delineate the specific areas in which CBT can be augmented through use of technology and outline the characteristics of an ideal therapy augmentor. Mobile telephones are identified as a low-cost and accessible device whose use has been largely untapped to date. The existing literature on use of the mobile phone is reviewed, and potential areas for its application in CBT are examined. The authors conclude with clinical guidelines for its use and the recommendation that use of mobile phones in CBT is a promising avenue for both clinical practice and research.