This paper identified and reviewed technological adjuncts to increase client adherence to therapy. Three areas of adherence were identified, namely treatment dropout and non-attendance, engagement during and between therapy sessions, and aftercare. Database searches were conducted in each of these areas to identify relevant studies published between the years of 1990 and 2010. Adjuncts designed to replace or reduce direct therapist contact, change the medium of communication between the client and therapist, or alter the content or style of the therapy were not included in this review. Adjuncts were reviewed in light of theories of adherence, including Self Determination Theory, the Transtheoretical Model, and the Theory of Planned Behaviour. Adjuncts reviewed included appointment reminders, exercises and monitoring delivered by mobile phone, and exercises and data collection delivered by computer. Limitations and directions for future research were addressed and discussed.