Behaviour change is an integral part of improved self-management of many chronic health disorders. Using mobile phones and text messaging to support behaviour change seems effective for people with different health conditions. CBT with focus on mindfulness and acceptance processes has been found to be effective for people with different chronic health disorders. Internet-administrated cognitive behavioural interventions are increasingly used to support people with health problems. Effective operationalization of important elements seems possible because, for some conditions, the effectiveness of internet-based CBT has been shown to be similar to that of face-to-face CBT. Results of a recent review of Internet interventions aiming to support behaviour changes indicate that interventions including mobile phone text messages and/or some personal online contact can be more helpful in supporting behaviour change than Internet interventions without those features (1). Today’s mobile phones commonly include an integrated internet facility, (e.g., personal digital assistants (PDAs) and smartphones), which opens new possibilities for internet-based CBT. By using a smart phone instead of a desktop or laptop computer, the patient can register and send information to the therapist when in different situations. An important goal of CBT is to improve functioning by detecting how automatic thoughts influence feelings and behaviour. The registration of thoughts and feelings can be done using the smart phone and may support self-monitoring. The internet connection makes it possible to submit this information online and make it immediately available to a therapist. The therapist is thereby provided with situational information with a reduced risk of memory bias. Importantly, this also enables the therapist to give the patient prompt feedback on the registered information via a text message. This thesis will explore application of CBT-based written situational feedback through the mobile phone in two different samples; one sample of persons with chronic pain, and one with persons having diabetes type-2. As data are registered electronically and daily, we will have the possibility to explore the process as well as the process related to health outcome. Thereby this thesis can contribute to the understanding of how CBT based smart phone interventions can lead to improved functioning and behavioural change. The intervention The intervention is an e-health intervention with intervention principles that can be applied to different patients groups. The general principles of the intervention are as follows: a) The patient fills out electronic diary forms with fixed content, specifically developed for the disease b) The patient will receive written tailored feedback on the mobile phone (webbased / SMS), based on the patients report at the moment ("situational feedback") c) The feedback is provided on the basis of cognitive behavior therapy (CBT) d) The feedback is given after a short time