Background: A large body of research has identified that many therapists do not use research to inform their practice, but few studies investigate the reasons behind this. Aims: The current study seeks to understand what sources therapists use to inform their practice and why they are chosen. Method: Thirty-three interviews with psychological therapists in the UK were undertaken. These were transcribed and analysed using Interpretative Phenomenological Analysis. Results: Two superordinate themes emerged. The former focused on the nature of evidence and the latter described why certain sources were used to make clinical decisions. When discussing evidence, participants felt that research studies, specifically Randomized Controlled Trials (RCTs), used unrepresentative samples. Therapists felt that research other than RCTs, particularly qualitative research, was important. Therapist specific factors were felt to be as, or more, important than the technique used to treat patients. When discussing the sources they used, therapists preferred to use their clinical experience or their patients’ experience to make clinical decisions. Theoretical or practical information was preferred to empirical research. The presentation of information was felt to be important to encourage the implementation of research, and therapists also felt tools such as outcome measures and manuals were too rigid to be useful. Finally, patients’ choice of treatment was felt to be important in treatment decisions. Conclusions: The views of therapists were heterogeneous, but this study highlighted some of the barriers to closing the gap between science and practice. This knowledge can be used to increase the translation of science into practice.