This paper reports on a methodological journey illustrating the need to reconsider the idea that the Randomised Control Trial (RCT) is the necessary ‘gold standard’ for psychotherapy research. The journey involved a systematic process undertaken to determine the most appropriate design and method for a specific psychotherapy research project. The processes involved in psychotherapy, including emotions and motivations (both conscious and unconscious), comprise an inherently complex system with many interrelated, uncontrollable and unpredictable variables. Studies that appear to be controlled and to provide statistical significance may mask an underlying failure and lack relevance to the dynamic realities of the consulting room. Consequently it is important to challenge researchers’ underlying assumptions about the nature of science. Within psychology the definition of ‘scientific’ often becomes confused with rigid adherence to particular methods, rather than recognising the core general feature of science to be critical inquiry. From that core it is argued that the most appropriate design for any scientific investigation is determined by the nature of the phenomenon under study. Hence, despite the pressure on psychotherapy researchers to use an RCT, the question must be asked whether any single method can be considered a gold standard independent of the phenomenon under study. This paper thus examines the application of the definition of science as critical inquiry to the dilemma of designing a scientifically rigorous psychotherapy research project.